Pituitary LH is a key factor in controlling Leydig cell activity. In order to verify how steroids produced by the male gonads could influence testicular insulin binding, different steroids at varying doses were administered. Testosterone propionate (Tp) as well as estradiol-17 beta (E2-17 beta) and 5 alpha-dihydrotestosterone (DHT) led to a 50% decrease of insulin binding in testis while no effect was noted when HCG was administered concomitantly with DHT. LH receptors were parallely measured: DHT and E2-17 beta significantly depressed testis LH binding. It is concluded that steroids play a role in the regulation of testis membrane insulin receptor via their feedback mechanism on pituitary LH.