Background: Mongolia’s long-term development policy, Vision 2050, aims to ensure that every citizen has full access to primary health care services and to increase the country’s average life expectancy. According to the “Primary Health Care Service Quality and Accessibility Survey,” the diagnostic capacity of family health centers (FHCs) in Mongolia was 42.1%. There is a need to further identify issues related to laboratory human resources, equipment supply, quality assurance, and monitoring. Aim: To assess the current status of laboratory diagnostic services in family health centers in Ulaanbaatar city. Materials and Methods: The study collected data using a questionnaire developed based on resources such as the WHO’s Service Availability and Readiness Assessment (SARA), USAID’s Laboratory Assessment Tools, the Ministry of Health’s 2023 Order No. A/283 on updated guidelines for services provided by family, soum, and bagh health centers, and the national standard “Structure and Operation of Family Health Centers (MNS 5292:2017).” A total of 46 FHCs in Ulaanbaatar were randomly selected for the study. Results: The average population served by the participating FHCs was 10,228±4043, with 73.9% (n=34) serving over 8,000 people. On average, each center employed 5±2 physicians and nurses. A clinical pathologist was employed at 50.0% (n=23) of the centers, of which 26.1% (n=6) were full-time and 73.9% (n=17) were contract-based. Availability of labo ratory equipment was as follows: Complete blood count (CBC) analyzers: 60.9% (n=28) Biochemistry analyzers: 50.0% (n=23) Urinalysis equipment: 97.8% (n=45) The availability of laboratory equipment was not significantly associated with the size of the population served (p=0.54; p=0.63; p=0.74). Among FHCs with laboratory equipment: 82.1% (n=23) performed CBC tests 87.0% (n=20) performed biochemistry tests 97.8% (n=44) conducted urinalysis tests. Participation in internal and external quality control programs was significantly higher among centers with specialized laboratory staff compared to those without (p=0.008; p=0.08). The number of tests and biochemistry parameters performed was also sig nificantly higher in centers with specialized laboratory personnel (p=0.001, p=0.001). However, the availability and use of rapid diagnostic tests did not differ based on population size or the presence of specialized laboratory staff (p=0.8; p=0.6). Conclusion 1. In Ulaanbaatar, only half of the family health centers have specialized laboratory personnel. 2. Laboratory equipment availability was between 50.0% and 60.9%. Centers with specialized laboratory staff showed significantly better performance in internal and external quality control and broader diagnostic testing services. 3. Differences in diagnostic services were associated with both the population size served and the availability of spe cialized laboratory staff, indicating the need to strengthen primary health care accessibility and capacity.