Large doses of stimulatory analogues of luteinizing hormone-releasing hormone (LH-RH) caused paradoxical antifertility effects. These effects are being utilized for the possible development of contraceptive methods. Several inhibitory analogues of LH-RH have been tested in men and women and shown to be active. The synthetic approach based on inhibitory analogues of LH-RH has been proven to be feasible for development of new methods of birth control. Continued research and testing along these lines may lead to the development of contraceptives based on inhibitory analogues of LH-RH that could be conveniently applied as a nasal spray and could be free of undesirable side effects.