The aim of the study is to identify the features of body mass index (BMI) and somatotypes in young men and men of mature age. Material and methods. By methods of comprehensive anthropometry and somatotyping assessed physical development 955 men of youthful and mature ages, ethnic Kyrgyz residents in Osh and its surroundings, healthy. Morphometric processing of the obtained data was performed using statistical programs Microsoft Excel and STATISTICA package. Results. Analysis of the data indicates that the representatives of all somatotypes body length increases slightly in the transition from adolescence to the 1st period of adulthood, with a further slight decrease in the 2nd period of adulthood. The conducted researches revealed constitutional and age features of body weight. In adolescence and adulthood it in abdominal somatotype more than in thoracic 1.4 times (p<0.05), compared with muscular - 1.1 times (p<0.05) and uncertain somatotype - 1.2 times (p<0.05). BMI in adolescence and adulthood in abdominal somatotype is greater than in thoracic 1.5 times (p<0.05) than in muscular - 1.3 times (p<0.05) and uncertain - 1.3 times (p<0.05). The tendency to increase the BMI values in the transition from adolescence to the 1st period of adulthood is shown. In the 2nd period of adulthood, compared with the youth, BMI increases by 1.1 times (p<0.05), except for men of muscular type, for whom this increase is not statistically significant. Conclusion. The conducted studies have revealed a tendency to increase the BMI values in the transition from adolescence to the 1st period of adulthood. In the 2nd period of adulthood, compared with the youth, BMI increases by 1.1 times (p<0.05), except for men of muscular type, for whom this increase is not statistically significant. The presented data on the age and somatotypological specifics of body length and weight, the value of BMI, is of great interest for preventive and clinical medicine.