The associations of five tissue-specific steroidal disorders with five human neoplasias, as detected in our case-control studies, have been related to the genesis of each tumor. Information from epidemiology, experimental pathology and molecular biology is in support of the notion that a specified environment exerts its carcinogenic action on the target tissue through the mediating action of the steroid-generating system. The usefulness of the concept of hormonal carcinogenesis in the search for the etiology of human cancer is emphasized using information available both from our laboratory and from outside sources.