Assessment of human body composition in vivo becomes increasingly important in medicine and sport. . The study of body composition plays the key role in diagnosis of obesity and osteoporosis, make possible monitoring and prescription of drug treatment. In sport, analysis of athlete’s body composition provides an effective method to control physical performance, and allows efficient management of athlete’s training process. It was shown relationship among body composition, physical performance, adaptation to environmental conditions, and professional and sports activities. It was found variation in body mass components related to a sport specifics, age and qualification of an athlete. The paper also provides list of techniques for body composition assessment.