Background: Skin wounds can occur for many reasons, including UV radiation, mechanical burns, trauma, and chronic inflammation caused by metabolic factors. In Mongolia, as of 2022, household burns were the top 5 causes of injuries, the leading cause of injuries in children aged 0-5, and accounted for 18.4% of all illnesses in children aged 0-5. Skin burns and wounds take a long time to heal, which causes emotional, aesthetic, and economic stress for doctors. Developing in novative, effective, and low-side effects therapeutic products to improve wound healing is of great clinical and economic importance. The lack of research on the effects of bacterial metabolites and aloe vera (Aloe barbadensis Miller) on burn wounds was the basis for our research. Aim: To determine the effects of a mixture of bacterial metabolites and aloe vera on burn wounds in experimental animals. Materials and Methods: Eight-week-old BALB/c mice were divided into three groups: control group, bacterial metabo lite group, and aloe vera group. The mice were anesthetized, and the dorsal hair was shaved over a 2×2 cm area using an electric clipper. A second-degree burn wound model was created by exposing the shaved dorsal skin to hot air at 200°C for 10 seconds. A total of 100 μL of a bacterial metabolite suspension mixed with aloe vera at a 1:1 ratio was applied evenly to the center of the wound. Wound images were captured daily, and wound areas were measured using ImageJ software. Healing was evaluated on days 7, 14, and 21 of treatment and compared with the control group. The initial wound size was defined as 100%, and wound closure percentages were calculated accordingly. Burn skin tissues from both experimen tal and control groups were subjected to immunofluorescence staining for the vascular marker α-SMA (Thermo Fisher Scientific). Statistical analysis: The differences between the control and experimental groups were analyzed using an independent t-test using GraphPad Prism 10 software, and the mean, standard deviation, and statistical correlation were calculated. Results: The effect of the mixture of bacterial metabolites and aloe vera (Aloe barbadensis Miller) on the healing of burn wounds in experimental mice was compared with the control group. The wound size at 7 days was 82.1% in the control group and 83.7% in the experimental group (p<0.197), at 14 days was 62.6% in the control group and 58.1% in the exper imental group (p<0.0001), at 21 days was 50.7% in the control group and 32.7% in the experimental group (p<0.0001). No statistically significant difference in wound healing was observed between the groups at day 7; however, significant differences were observed at days 14 and 21. Immunofluorescence analysis revealed uniform expression of α-SMA-pos itive cells in the experimental group at 7, 14, and 21 days of treatment, whereas α-SMA expression was not detected in the control group. Conclusion The combination of bacterial metabolites and aloe vera promotes wound healing in experimental mouse burn wounds.

Background: Hemophilia is a congenital bleeding disorder caused by a lack of clotting factor in the blood. Hemophilia A, B, and C are caused by congenital deficiencies of clotting factors VIII, IX, and IX which are involved in thrombin generation of intrinsic coagulation pathway. Hemophilia A and B is a recessive X-linked congenital bleeding disorder but hemophilia C is typically inherited in an autosomal recessive, these are rare inherited coagulation disorders. This study was conducted based on the lack of database on the epidemiology, clinical type and severity in hemophilia in Mongolia. Aim: The aim of this study was to investigate the relationship between clotting factor levels and bleeding severity of hemophilia. Materials and Methods: A cross sectional study included a total of 30 patients with hemophilia who were registered from May to October 2025 at the Comprehensive Hemophilia Center, MNUMS. The study was approved by the Research Ethics Committee of MNUMS. Result: In this study 30 patients with hemophilia mean age was 18.4±15.7 years, and 96.7% were male. When categorized by age group, 13.4% (n=4) were under 4 years, 40% (n=12) were 5–13 years, 10% (n=3) were 14–18 years, 33.3% (n=10) were 19–44 years, and 3.3% (n=1) were over 45 years. Of the total cases, 83.3% (n=25) had Hemophilia A and 16.7% (n=5) had Hemophilia B. Of the total case, 80% of cases were classified as severe and 20% as moderate hemophilia. Additionally, 40% of cases had joint complications. Conclusion Joint bleeding was observed in 41.6% of patients with severe hemophilia and in 33.3% of those with moderate hemophilia. Target joint damage was found in 40% of the study population because 86.6% of patients were not able to receive prophylactic factor replacement therapy. Joint damage, joint deformities, reduced range of motion, and deterioration in quality of life were all adverse outcomes related to the early onset of joint bleeding.

Background: Globally, research on identifying bioactive compounds from medicinal plants and characterizing their in vitro and in vivo pharmacological activities is progressing rapidly. Plants native to Mongolia have adapted to unique, extreme continental climatic conditions, accumulating distinct phytochemicals, and have historically been utilized in traditional medicine and dietary practices. Establishing the non-cytotoxic safety threshold of these wild and cultivated plant extracts in RBL-2H3 mast cells a universally accepted model for type I hypersensitivity and inflammation is a vital prerequisite. Determining these baseline non-toxic dose ranges provides the essential scientific foundation for subsequent cellular allergy models, animal studies, and the elucidation of molecular mechanisms underlying their therapeutic efficacy. Aim: To determine the cytotoxicity profile and establish the non-cytotoxic dose ranges of extracts from four selected Mongolian plant species (wild and cultivated) in RBL-2H3 cells. Materials and Methods: Plant samples including lingonberry (Vaccinium vitis-idaea), strawberry (Fragaria orientalis), black radish (Raphanus sativus), and blue-berried honeysuckle (Lonicera caerulea L.) were standardly collected, authenticated, and cataloged as herbarium specimens at the Botanic Garden and Research Institute, Mongolian Academy of Sciences. A total of 12 distinct extracts were prepared from plant leaves, stems, and fruits using water and ethanol extraction, followed by concentration via rotary evaporation and freeze-drying. Rat basophilic leukemia (RBL-2H3) cells were maintained in EMEM growth medium and utilized during the exponential growth phase. Cell viability and non-cytotoxic concentration thresholds were evaluated using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Result: Ethanolic extracts of strawberry leaves, black radish, and honeysuckle leaves (≥6.25 µg/mL), as well as aqueous extracts of honeysuckle fruits (≥6.25 µg/mL) and stems (≥25 µg/mL), exhibited dose-dependent cytotoxicity. Conversely, aqueous extracts of lingonberry leaves (≤200 µg/mL), strawberry leaves (≥100 µg/mL), and black radish (≤200 µg/mL), alongside ethanolic extracts of lingonberry leaves (≥50 µg/mL), demonstrated non-cytotoxic profiles. Furthermore, ethanolic extracts of honeysuckle stems (≤300 µg/mL) and fruits (≥12.5 µg/mL), as well as the aqueous extract of honeysuckle leaves (≤50 µg/mL), significantly enhanced RBL-2H3 cell viability. Conclusion The tested plant extracts influenced RBL-2H3 cell viability in a solvent polarity and plant organ dependent manner. Ethanolic extracts of strawberry leaves, black radish, and honeysuckle leaves, along with aqueous extracts of honeysuckle fruits and stems, demonstrated relatively high cytotoxicity, reducing cell viability by >40% starting at concentrations of 12.5, 25, and 50 µg/mL. In contrast, aqueous extracts of strawberry leaves and black radish, as well as both aqueous and ethanolic extracts of lingonberry leaves, maintained low cytotoxicity at concentrations below 200 µg/mL. Notably, ethanolic extracts of honeysuckle stems and fruits (>12.5 µg/mL) and its aqueous leaf extract (<100 µg/mL) enhanced cell viability, exhibiting significant cell proliferation promoting activity.

Background: According to the World Health Organization’s 2022 Global Oral Health Status Report, approximately 3.5 billion people worldwide - nearly half of the global population - suffer from some form of oral disease, among which dental caries is the most prevalent, affecting close to 2 billion people in permanent teeth (global average prevalence of 29%) and 514 million people in primary teeth (global average prevalence of 43%). In Mongolia, the prevalence of dental caries also remains high: a 2017 survey of 1,754 individuals from six provinces and five districts found caries prevalence of 82.9% among children under 5 years of age, 80.9% among those under 12, 97.8% among the population aged 35-44, and 99.1% among those aged 65-74. A 2010 study among Mongolian preschool and school-age children found a caries prevalence of 87.8-90%, with S. mutans identified alone in 75% of culture-positive plaque samples and together with S. sobrinus in the remaining 25%. Given the persistently high global burden of dental caries, preventing the disease rather than merely treating it - for example through “replacement therapy,” in which a less cariogenic strain of S. mutans is used to colonize the oral cavity - requires a reliable rat model in which standard and clinical strains of S. mutans can reproducibly induce dental caries, so that the efficacy of such preventive strategies can be properly evaluated. Untreated dental caries is also estimated to impose an annual global economic burden of approximately US$387 billion in direct costs and US$323 billion in indirect costs, underscoring the growing importance of research into new preventive approaches. Aim: Development of a dental caries model caused by Streptococcus mutans infection in rat teeth. Materials and Methods: This study used an experimental research design. It was conducted from March 30 to April 14, 2021, at the Core Laboratory and the Education Laboratory of the Department of Microbiology and Infection Prevention Control of the Mongolian National University of Medical Sciences (MNUMS). Ethical approval was obtained from the Medical Ethics Review Committee under the Ministry of Health (meeting No. 02, March 18, 2019). Five 8-week-old Wistar rats were divided into four experimental groups - differing by bacterial strain (S. mutans ATCC 25175 standard strain versus a clinical isolate) and by drinking-water composition (with or without sucrose) - plus one negative control group, with one rat assigned to each group. A bacterial suspension was applied to the rats’ molar teeth with a sterile cotton swab three times daily at two-hour intervals for 28 consecutive days. Rats were lightly sedated with midazolam during application, and the suspension was applied during the daytime, when salivary flow is naturally reduced in rodents, in order to promote bacterial colonization of the tooth surface. Result: On day 28, microscopic examination of each rat’s maxillary and mandibular teeth revealed carious spots and cavities in all groups except the sucrose-free negative control. Cavities were deeper in the groups that received sucrose-supplemented drinking water, whereas the sucrose-free groups showed comparatively milder lesions, indicating that bacterial infection alone was sufficient to induce caries. Conclusion Infection of 8-week-old Wistar rats with either the standard or a clinical strain of S. mutans for 28 days successfully induced dental caries, and sucrose intake increased the severity of the lesions. This baseline model can be reproduced within a relatively short time frame and at low cost, and may be applied in future studies evaluating the efficacy of replacement-therapy strains or probiotic products against dental caries.

Background: Helicobacter pylori is a highly prevalent pathogen infecting more than half of the global population, with considerable geographic variation in its genetic characteristics and antibiotic resistance patterns. The EPIYA motifs of the CagA protein play a critical role in bacterial virulence; however, data on the association between CagA genotypes and antibiotic resistance remain limited in Mongolia. Aim: To determine the antibiotic resistance, CagA EPIYA patterns, and clarithromycin resistance-associated mutations of H. pylori strains in Mongolia, and to evaluate the agreement between phenotypic and molecular diagnostic methods. Materials and Methods: Gastric biopsy specimens were collected from 210 patients undergoing endoscopy and cultured for H. pylori. Antibiotic susceptibility to metronidazole, clarithromycin, amoxicillin, levofloxacin, and tetracycline was determined using the E-Test method according to EUCAST guidelines. CagA EPIYA patterns were analyzed, and clarithromycin resistance-associated mutations (A2142C, A2142G, A2143G) were detected using real-time PCR. Result: H. pylori was successfully cultured in 86 of 210 samples (41%), and 61 isolates were included in the final analysis. CagA-positive strains accounted for 86.9%, with a predominance of Western-type CagA (52/53), while only one East Asian-type strain was identified. Among Western-type strains, the ABC (58.5%) and ABCC (37.7%) patterns were most common. The highest resistance rate was observed for metronidazole (70.5%), followed by levofloxacin (50.9%). Clarithromycin and amoxicillin resistance were both 19.7%, whereas no resistance to tetracycline was detected. Multidrug resistance (≥2 antibiotics) was observed in 45.9% of isolates, and 14.8% showed resistance to ≥3 antibiotics. Clarithromycin resistance-associated mutations were detected in 21.3% of isolates, predominantly A2143G. The agreement between E-test and real-time PCR methods was excellent (κ=0.95, p<0.001). Conclusion H. pylori strains in Mongolia are characterized by a predominance of Western-type CagA, with ABC and ABCC as the most common subtypes. Notably, the AAABC and AAAAB subtypes were identified for the first time. High levels of antibiotic resistance, particularly to metronidazole and levofloxacin, as well as a substantial prevalence of multidrug resistance, highlight the need for region-specific treatment strategies. In Mongolia, H. pylori demonstrated the highest resistance to metronidazole, accompanied by a high proportion of multidrug-resistant isolates.

Background: Conventional methods for assessing exposure to environmental tobacco smoke rely mainly on questionnaires and biomarkers with short half-lives, such as urinary cotinine. In contrast, oral mucosal pigmentation may represent a visible, non-invasive biomarker of chronic exposure. However, its clinical and policy relevance, as well as its validity for screening purposes, remain insufficiently established. Aim: To summarize the evidence on the association between exposure to environmental tobacco smoke and oral mucosal pigmentation and to assess some confounding factors. Materials and Methods: We synthesized findings from observational studies that examined the association between environmental tobacco smoke exposure and oral mucosal pigmentation across all age groups. International electronic databases, including PubMed, Embase, Web of Science, and Scopus, were searched. Data were extracted on exposure–response relationships, measurement instruments, anatomical distribution of pigmentation, confounding by physiological pigmentation, and biochemical validation. The quality of included studies was assessed using the Mixed Methods Appraisal Tool (MMAT). A narrative synthesis was conducted, focusing on the biological plausibility of the biomarker, standardization of measurement, and its potential implications for screening and tobacco control policy. Results: Thirteen observational studies from seven countries, involving a total of 3,284 participants, met the inclusion criteria. Four studies reported a statistically significant association between duration of exposure and severity of pigmentation, while one cohort study showed that urinary cotinine levels increased with age among children. The Gingival Pigmentation Index and the Dummett Oral Pigmentation Index were the most commonly used assessment tools; however, methodological heterogeneity limited direct comparability across studies. The anterior gingiva was the most frequently affected anatomical site. Only a limited number of studies adequately controlled for physiological pigmentation, and skin color was identified as an important confounding factor. The pooled odds ratio was 2.35; however, the certainty of evidence was low due to the observational nature of the included studies. Conclusion Oral mucosal pigmentation may serve as a potential biomarker of long-term exposure to environmental tobacco smoke. Nevertheless, standardized assessment protocols, adequate control for physiological pigmentation, and validation against “gold-standard” biomarkers are required. If validated, this marker could be used for rapid identification of high-risk groups and incorporated into tobacco control policies.

Background: Human papillomavirus (HPV) is the primary cause of cervical cancer, with HPV genotypes 16 and 18 classified as high-risk types. In Mongolia, HPV testing has been increasingly implemented in recent years, alongside updates to the national screening program. These developments highlight the need for additional testing approaches to encourage regular participation in the national screening program, improve diagnostic accuracy, and facilitate timely treatment planning. These considerations provided the rationale for this study. Aim: To detect HPV infection in cervical samples collected by healthcare professionals and vaginal samples self-collected by women, determine the concordance between the test results, and evaluate the feasibility of self-sampling for cervical cancer screening. Materials and Methods: A total of 206 women aged 25–68 years participated in the study. Two types of samples for HPV testing and one sample for PAP smear were collected from the participants. 14 high-risk of HPV genotypes were classified into three groups, and cytological findings were evaluated according to the 2014 Bethesda System. Statistical analyses were performed using SPSS version 30.0. Results: The concordance between the two sampling methods for HPV detection kappa was 0.949. High-risk HPV genotypes were detected in 50 women (35.2%) among the participants with available test results. Cytological abnormalities were identified in 51% of women who tested positive for HPV. Conclusion Self-sampling is a reliable method for HPV detection, demonstrating good concordance with healthcare professional-collected cervical samples. It has considerable potential to increase cervical cancer screening coverage and improve access to screening, particularly in geographically remote areas.

Background: Recent international studies have demonstrated that vaginal microbiota dysbiosis is associated with persistent human papillomavirus (HPV) infection, cervical precancerous lesions, and cervical cancer. In healthy women, Lactobacillus spp. dominate the vaginal microbiota and produce lactic acid and other bioactive compounds, thereby maintaining an acidic vaginal pH and protecting against colonization by pathogenic microorganisms. A reduction in Lactobacillus spp. and overgrowth of pathogenic bacteria, resulting in dysbiosis, has been associated with HPV persistence as well as the progression and recurrence of cervical precancerous lesions. However, no study has compared the prevalence of Lactobacillus spp. and aerobic bacteria, or their associations, among Mongolian women diagnosed with cervical precancerous lesions or cervical cancer. Therefore, this study was conducted to address this gap. Aim: To compare and characterize the composition of selected vaginal microorganisms in women diagnosed with cervical precancerous lesions and cervical cancer. Materials and Methods: This hospital-based, cross-sectional study was conducted from May to October 2026 at the Department of Gynecologic Oncology, National Cancer Center of Mongolia. A total of 275 women with histologically confirmed cervical precancerous lesions or cervical cancer were voluntarily enrolled after providing written informed consent. Prior to initiation, ethical approval was obtained from the Research Ethics Committee of the Mongolian National University of Medical Sciences at its meeting held on April 22, 2026 (Minutes No. 2026/04-28). General information, medical history, and behavioral factors were collected using a structured questionnaire. Three vaginal swabs were collected from the posterior vaginal fornix. Vaginal discharge was examined, and Lactobacillus spp. and aerobic bacteria were cultured. The associations between these microbiological findings and diagnostic groups were compared across five diagnostic categories. Results: Of the 275 women enrolled, the diagnostic distribution was as follows: CIN I, 41 (14.9%); CIN II, 73 (26.5%); CIN III, 80 (29.1%); cervical carcinoma in situ (CIS), 45 (16.4%); and cervical cancer (CC), 36 (13.1%). Vaginal pH was significantly and positively correlated with the cocci count (ρ=0.346, p < 0.001), white blood cell count (ρ=0.283, p < 0.001), and AV score (ρ=0.277, p < 0.001). In contrast, the Lactobacillus count was significantly and negatively correlated with vaginal pH (ρ=−0.238, p < 0.001). When the AV score was compared across diagnostic groups, it was 2.8±1.3 in stage IIB cervical cancer and 3.67±2.3 in stage III cervical cancer (p=0.008). Lactobacillus spp. were isolated from 119 participants (43.3%), while aerobic bacteria were isolated from 103 participants (37.5%). The most frequently identified aerobic bacteria were Escherichia coli (32; 11.6%), Enterococcus faecalis (17; 6.2%), Streptococcus agalactiae (11; 4.0%), and viridans group streptococci (9; 3.3%). However, the detection rates of Lactobacillus spp. and aerobic bacteria did not differ significantly across diagnostic groups (p=0.634 and p=0.221, respectively). Conclusions Among women with cervical precancerous lesions and cervical cancer, an increase in vaginal pH was significantly positively associated with cocci count, white blood cell count, and AV score. The higher AV scores observed in the cervical cancer group suggest that aerobic vaginitis may be associated with the progression of cervical precancerous lesions. Although the prevalence of Lactobacillus spp. and aerobic microorganisms did not differ significantly across diagnostic groups, the CC group showed a trend toward increased prevalence of aerobic microorganisms and decreased prevalence of Lactobacillus spp.

Background: HepG2 cells are widely used as an in vitro model for investigating alterations in hepatic cellular metabolism. Studies evaluating the biological activities of plant-derived compounds using HepG2 cells have also increased. Strawberry (Fragaria orientalis), lingonberry (Vaccinium vitis-idaea), radish (Raphanus sativus), and blue honeysuckle (Lonicera caerulea L.) contain polyphenols, flavonoids, anthocyanins, and other secondary metabolites. The biological activities of these plants may vary depending on species, plant tissue, growing conditions, and extraction methods. Prior to evaluating the biological activities of plant extracts, it is essential to assess their cytotoxic effects on cells and determine appropriate concentrations for subsequent experiments. Therefore, evaluating the effects of plant extracts on the viability of HepG2 cells, a human hepatocellular carcinoma cell line, is of considerable importance. Aim: To evaluate the effects of aqueous and ethanolic extracts of strawberry, lingonberry, radish, and cultivated and wild blue honeysuckle on HepG2 cell viability and to determine concentrations exhibiting cytotoxic effects. Materials and Methods: A total of 18 plant extracts were prepared using water and ethanol as extraction solvents. The extracts were obtained from strawberry leaves, lingonberry leaves, radish, and the fruits, stems, and leaves of cultivated and wild blue honeysuckle. The extracts were subsequently dried. HepG2 cells maintained in the Cell Biology Laboratory of the Institute of Biomedical Sciences were revived, stabilized, and used for the experiments. The plant extracts were prepared at concentrations of 6.25, 12.5, 25, 50, 100, 200, and 300 μg/mL and used to treat HepG2 cells. Cell viability was assessed using the Cell Counting Kit-8 (CCK-8) assay. Cytotoxicity was defined as a reduction in cell viability of more than 30% compared with the control group. Results: The aqueous extract of cultivated blue honeysuckle and the ethanolic extracts of its fruits and stems maintained HepG2 cell viability above 70% across the concentration range of 6.25–300 μg/mL, indicating relatively low cytotoxicity. In contrast, the ethanolic extract of cultivated blue honeysuckle leaves reduced cell viability at higher concentrations. The aqueous and ethanolic extracts of fruits and stems of wild blue honeysuckle showed no apparent cytotoxic effects, whereas both aqueous and ethanolic extracts of its leaves reduced cell viability to approximately 65% at 300 μg/mL, indicating relatively higher cytotoxicity. Most aqueous and ethanolic extracts of strawberry, radish, and lingonberry maintained cell viability above 70% and showed no cytotoxic effects. The ethanolic extract of strawberry leaves reduced cell viability to approximately 63% even at the lowest concentration of 6.25 μg/mL; however, cell viability tended to increase with increasing extract concentration. Conclusion The effects of plant extracts on HepG2 cell viability varied depending on plant species, tissue type, extraction solvent, and concentration. Most extracts of strawberry, lingonberry, radish, and the fruits and stems of cultivated and wild blue honeysuckle exhibited relatively low cytotoxicity at concentrations ranging from 6.25 to 300 μg/mL. However, the ethanolic extract of cultivated blue honeysuckle leaves at 200 μg/mL and the aqueous and ethanolic extracts of wild blue honeysuckle leaves at 300 μg/mL reduced cell viability by more than 30%, indicating relatively higher cytotoxicity.

Background: Hepatitis virus infections are widespread and highly endemic in Mongolia and ranks first in the world for liver cancer mortality per 100,000 population, eight times the world average. The World Health Organization estimates that more than 2 billion people are infected with the hepatitis B virus. Each year, 1 million people die from the infection, 4 million are newly infected, and approximately 350-400 million are chronic carriers. In 2018, 475 cases of viral hepatitis were recorded nationwide, accounting for 1.1 percent of all communicable diseases, a decrease of 59 cases or 0.2 per 10,000 population compared to the previous year. In 2016, 194 WHO member countries joined forces to develop a strategy to reduce viral hepatitis, with the goal of reducing mortality by 65% and new infections by 90% by 2030. In order to achieve this goal, the strategic goal states that each country must conduct a comprehensive public health study and intervention on the spread of infection, risk factors, and early detection. Aim: Study to the coverage of hepatitis B immunization among children aged 0-9 years in urban and rural Mongolia and to determine the influencing factors. Materials and Methods: A Nationwide population based cross-sectional study design was used in this study. Mongolia is geographically divided into the western, Khangai, eastern, and central regions. A total of 14 provinces were selected randomly in addition to Ulaanbaatar city. The appropriate sample size was estimated at 4500 children aged 0-9 years, based on 2019 demographic data from the National Statistics Office. The questionnaire contained closed and semi-closed questions on demographics, socio-economic status, vaccination history and etc. Results: A total of 5027 children aged 0-9 years were enrolled in this study out of which 33.7% (n=1692) and 66.3% (n=3335) were enrolled from capital city Ulaanbaatar and provinces, respectively. Almost half (n=2552) of the study participants were boys whereas the remaining were girls 50.0% (n=2554). According to the history of Hepatitis B vaccination by questionnaire of parents’, 91.2% [91.2-92.0] were vaccinated with Hepatitis B. The proportion was 89.7% [89.7-90.8] and 94.1% [94.1-95.2] in rural and urban areas, respectively. Nearly 90% [89.6-90.5] of children were vaccinated in hospitals, 2.3% [2.0-5.0] were vaccinated at home, 8.1% [7.9-10.7] were unaware of the study participants’ location of vaccination. There were no statistically significant differences by urban and rural residences. Vaccination coverage against Hepatitis B was 91.5% (n=2300) and 90.9% (n=2284) among boys and girls, respectively and 89.6% (n=4506) were vaccinated at hospitals. Vaccination coverage were similar by sex. We also used Health Documents /pink book of children/ or vaccination card for each child to determine the coverage. According to the data from the children’s vaccination card and health documents’, 917 (18.2%) children were not vaccinated against hepatitis, 57 (1.1%) children received 1 dose, 235 (4.7%) children received 2 doses, and 3818 (75.9%) children received all 3 doses of hepatitis B vaccine. There was no significant difference by sex, though the coverage varied by age. For instance, proportion of children with no written documentation in the vaccination card was 13.5% among children aged 1 years that increased to 22.5% and 25.3% among children aged 8 and 9 years, respectively. In contrast the coverage rate of 3 doses of hepatitis B vaccination declined from 77.8% to 70.7% among children aged 1 years and 9 years, respectively. Hepatitis B vaccination coverage according to the vaccination card was different by provinces and within the districts of Ulaanbaatar city. Conclusion A total of 5027 children aged 0-9 years were included in the study, of which 917 (18.2%) children were not vaccinated against hepatitis, 57 (1.1%) children were vaccinated against the first dose, 235 (4.7%) children were vaccinated against the second dose, and 3818 (75.9%) children were fully vaccinated against the first-third dose. Although the coverage of the study participants varied depending on age and place of residence, no significant differences were observed in terms of gender. The current rate of children who are not fully vaccinated stands at 18.2%, emphasizing the need to ensure all children receive full vaccinations for hepatitis B and the required five doses as per the schedule. Furthermore, it is essential to mandate booster vaccinations for those with delayed immunizations and improve the accuracy of registration data.