Vitamin D deficiency is a major health problem worldwide, especially in the elderly, so that an accurate assessment of its prevalence is essential for planning reliable healthcare policy throughout the lifespan. Purpose: The aim of the oncentrationofpresent study wasto assess the25-hydroxyvitamin D 25OHD) across different as well as the mild andmoderate deficiencies ages and genders. Methods: We searched the database of the local Laboratory Information System to retrieve results of 25OHD tests performed on the whole cohort of presumably Mongolian participants aged >22 yrs, who were referred to our laboratory in Gurvan Gal Hospital’s clinical laboratory, a 1-year period (January 2011 - January 2012). Results: Results for 25OHD testing were retrieved for 120 participants. No significant differences between females and males were observed for 25OHD values(20 [4-17.89]ng/ml versus 53 [4-20.06]ng/ml; p=0.3). A non significant variation of 25OHD values was also found by ANOVA analysis throughout 3 age cohorts (22-40, 41-60, >60 yrs), in both genders. In each age group, the values of 25OHD did not significantly differ between genders. Conclusions: We observed a high prevalence of vitamin D deficiency in a Mongolians. Lifestyle factors, including smoking, and physical activity, were significant predictors of serum 25-hydroxyvitamin D concentration.