[The vanishing gender?]

The literature data indicating a significant impairment of the basic parameters of male reproductive function in the last decades are analyzed and summarized. This impairment is expressed in the reduction of spermatogenic activity, increased incidence of genital malformations and testicular tumors. The listed changes are reviewed in comparative aspect and include examples of some species of wild animals. The data on the factors responsible for occurrence of pathological changes in male reproductive system are analyzed.