The compositional content of the body of athletes is one of the factors that can affect the effectiveness of sports activity, being an important component of the training process of football players. In turn, the composition of the body depends on the orientation, intensity and volume of training loads. Physical activity and exercise are known to lead to a decrease in body fat and an increase in lean body mass. The purpose of the study was to determine the significance of body composition for functional readiness of football players. Material and methods. The research involved 81 football players (Ukrainian Premier League), aged 20-30 years. During the research, the following methods were used: chronometry, ergometry, spirometry, gas analysis, heart rate monitoring, anthropometry and impedance measurement, biochemical research methods, and mathematical statistics methods. Results and discussion. As a result of the study, we established the influence of the body composition, in particular the percentage of body fat, on the level of functional readiness of football players. The probable correlations between the values of the level of functional readiness and indicators of the composition of the body were revealed. We found probable correlation between lean body mass and absolute power (r = 0.90; p ≤ 0.05), lean mass and VO2max (r = 0.44; p ≤ 0.05). A probable correlation between the percentage of fat and specific power (r = - 0.45; p ≤ 0.05), the percentage of fat and speed (r = - 0.50; p ≤ .05) was also revealed. An increase in body fat mass can negatively affect the specific power, speed and aerobic capabilities of athletes; it manifests itself in a decrease in the VO2max, speed and power of football players with an increase in body weight due to the fat component. Conclusion. The highest values of maximum power and VO2max were achieved by football players with adipose tissue content in the range from 9.0 to 16.0%. An increase in the level of functional readiness of football players is possible by optimizing the compositional composition of the body of athletes, namely, the percentage of body fat