Recently growth hormone therapy has been used as an age delaying drug in middle aged men and women as well as in the elderly. Positive effects have been shown in regards to body mass and body composition changes, fat metabolism, bone mineral density and muscle strength. Exercise is a potent physiological stimulus for growth hormone secretion and both aerobic and resistance exercise results in significant, acute serum increases in GH concentration. It is unclear however whether a combination of exercise and hGH therapy further increases physical performance in adults and increases changes in body composition and biochemical variables related to health. For this purpose a group of 15 middle aged men (45,7±5,8 years, 93,2±16,3kg and 183,3±4cm), slightly overweight were randomly divided into an experimental and control groups. Both groups exercised for 3 month, performing 2 aerobic sessions per week and 2 resistance workouts, increasing training loads every two weeks. The experimental group received additionally hGH subcutaneous injections beginning with 0,2 IU daily for the first month and then increasing it to 0,4 and 0,6 IU in successive month. VO2max was evaluated during a progressive ergocycle test to volitional exhaustion, while anaerobic power and capacity were measured during the 30s Wingate test. Additionally body mass and body composition were evaluated as well as the lipoprotein profile and the concentration of chosen anabolic hormones. The results indicate a significant rise in resting concentrations of GH and IGF-1 after the replacement therapy but no additional benefits in regards to aerobic fitness and fat metabolism in comparison to exercise only. A more profound effect was observed in case of anaerobic performance, thus it was concluded that even small doses of hGH stimulated additional protein synthesis following resistance exercise what allowed for significant increases in FFM, anaerobic power (W/kg) and capacity (J/kg) as evaluated obtained during the Wingate test. It was concluded that for a more significant effect of hGH therapy in regards to physical performance greater doses of this hormone have to be used, along with an intensive exercise program.