Aging in males is accompanied on the one hand by a progressive decline of plasma testosterone levels and on the other hand by a series of signs and symptoms reminiscent of the symptomatology of hypogonadism in young males. It therefore seems reasonable to assume a role of low testosterone levels in this symptomatology. The latter, however has a multifactorial origin, with decreased growth hormone levels , relative sedentarism, obesity and insulin resistance playing a role. Hence it is not surprising that correlations between symptoms and testosterone levels are generally weak, although often statistically significant. The exact role of the relative hypogonadism in this symptomatology remains, nevertheless still difficult to define and androgen supplementation should only be considered in the presence of both evident symptoms and subnormal testosterone levels. Experience with androgen substitution in elderly males remains still very limited and very few studies covered a period exceeding one year. From these studies it can cautiously be concluded that androgen treatment of elderly men may have some beneficial effects on muscle mass, body fat, libido and possibly bone mass. The most evident effects are the lower basal testosterone levels. However, beneficial effects on clinically relevant parameters such as falls, fractures heart infarction or mortality have, so far, not been reported. The long term risks and benefits ratio remains largely unknown, although so far, treatment seems to be rather safe, but careful monitoring for side effects, in particular at the level of the prostate, remains mandatory