Recent years have seen an increasing interest in the study of the aging male , with particular interest in the male hormone replacement can improve quality of life (Vermulin 2001). The study was designed to investigate the effects of testosterone replacement on GH & PRL exercise responses in castrated male rats. Fifty six adult male albino rats were included in the study. The rats were classified into seven groups: gp I sham castrated, gp II Exercised sham castrated, gp III castrated, gp IV exercised castrated, gp V exercised castrated testosterone replacement (10 mg / Kg/ week), gp VI exercised castrated testosterone replacement double dose, gp VII exercised castrated testosterone replacement half dose. After i month of experiment all rats were sacrificed, blood samples were collected and GH & PRL level were estimated in all samples. Our results showed that exercise increase both GH & PRL in sham castrated rats. This response is abolished in castrated rats.Testosterone replacement increases both GH & PRL response to exercise and this effect is dose dependent. We conclude a beneficial effect of testosterone replacement in old aged men with moderate training will improve bone mass and prevents the unfavorable changes in organs upon which androgen acts through increase GH & PRL response to exercise.