It has been reported that circulating androgens exhibit a decrement with aging in men; however, there are some controversial results. We have carried out a descriptive study in a group of men aged 60-70 years. In order to determine levels of androgens In serum, the results were compared with those obtained in another group in normal men 20-44 years of age. Measurements included circulating levels of testosterone(T), dehydroepiandrosterone sulfate (DHEA-S), LH, FSH, estradiol (E), ACTH, prolactin (PRL), IGF-1, and SHBG. The group of older men group showed a significative decrement of T and DHEA-S, as well as E. An increment of FSH and LH without changes of ACTH, cortisol and SHBG was demonstrated. Collaterally, PRL and IGF-1 decreased in aging men. The present data demonstrated a significant decrement of circulating androgens, both T and DHEA-S coinciding with elevation of gonadotropins. It is concluded that aging is accompanied by changes of a decrement of androgens, of gonads, and adrenal origin. Further studies will investigate the effect of testosterone replacement in aging men.