Background: As the world population ages, the prevalence of osteoporosis is increasing, becoming a major health problem. In Mongolia, a trend of bone structural changes and fractures due to metabolic syndrome and its complications has been observed in a study by Baatar N (2017). However, the lack of research on the relationship between central obesity indicators such as neck circumference and bone mineral density, was the reason for conducting this study. Aim: To determine the relationship between neck circumference, an indicator of central obesity, and bone mineral density among citizens attending the First National Central Hospital. Materials and Methods: This study was conducted using an analytical cross-sectional study design. A total of 224 participants aged 30 years and older were included in the study. Participants’ lifestyle and health questionnaires were collected using a standard questionnaire, and anthropometric measurements (neck circumference, waist circumference, height, and weight) were performed. Bone mineral density was measured and evaluated using the EXA-PRESTO (Osteo Sys, 2022) device. The results of the study were processed using the SPSS-26.0 program. Results: There was no statistically significant difference in the association between gender and osteoporosis. The chi-square test (χ²=1.132, p=0.287) showed that gender was not associated with osteoporosis. The odds ratio (OR) analysis showed that women were 1.33 times more likely to develop osteoporosis than men (OR=1.33, 95% CI: 0.78–2.27), but this difference was not statistically significant (p > 0.05). When neck circumference was stratified into groups, there was no statistically significant association in women (χ²(4)=3.137, p=0.535), but in men the association was significant when the neck circumference was ≤ 39 cm (χ²(4)=10.192, p=0.037). Conclusion The results of the study showed that the female group had a higher risk of osteoporosis than the male group (OR=1.33), but this difference was not statistically significant (p>0.05). This may be due to changes in bone metabolism due to hormonal changes in women, especially the decrease in estrogen.