A survey was conducted in a representative sample of Mongolia's urban and rural population aged 25-64 years. The paper gives the data on the prevalence of overweight and obesity depending on age, gender and place of residence, which have been obtained in the survey of a representative sample of the Mongolian population examined twice at a 4-year interval with 95.8 and 97.4% responses during the first and second surveys, respectively. All the respondents were inquired according to the standard questionnaire and underwent anthropometric measurements (body weight and height). In the population of Mongolia, the prevalence of obesity in 2013 was 18.4±1.2% for the men and 28.1±1.6% for the women. The men had a lower body mass index and a lower frequency of obesity than the women. Over 4 years, the prevalence of obesity increased from 19.6 to 28.1% in the women (p<0.001) and from 16.0 to 18.4% in the men (p=0.1). In all age groups, the increased prevalence of overweight and obesity was significantly higher in the women than in the men. The relatively high increment rate of the prevalence of overweight and obesity was revealed in the 45-54-year-old population of Mongolia. The rise in overweight and obesity rates was mainly due to 1.2- and 1.4-fold increases in the proportion of overweight and obese rural residents, respectively. Over the 4 years, the representative sample of Mongolia's population showed 1.1- and 1.3-fold increases in the number of the examined overweight and obese individuals in the general adult population, which determines the development and progression of non-communicable diseases in the population of Mongolia.