A transient physiologic period similar to that in women leads from full sexuality to senium in the life of men, too. This phase may involve the complex of male climacteric symptoms. The diminished testosterone secretion of the testes as endocrine "primum movens", together with an increased level of the carrier protein (SHBG), results in a reduced androgen supply of the organism, as reflected in a low free androgenic index. The diagnosis of male climacteric is made on the basis of an enhanced serum LH level. With regard to the differential diagnosis, atherosclerosis, diabetes mellitus, chronic alcoholic liver damage, malignant tumors and prostatic complaints are particularly to be considered. The hormonal treatment consists of low-dose testosterone medication; for the prevention of osteoporosis, however, testosterone preparations may be replaced by anabolic steroids. As for women, the concomitant vegetative phenomena of the climacteric syndrome should be alleviated symptomatically.