At a meeting in Geneva, a group of scientists tried to summarize the current status of contraceptive methods. Experiments with methods influencing spermiogenesis have so far been unsuccessful. Estrogens and gestagens block the secretion of gonadotropins which influence spermatogenesis, but at the same time they strongly affect the libido. Derivatives of aziridin and esters of metanesulfonic acid damage spermatogenesis, but are toxic at the same time. The inhibition of ovulation has been succesfully studied and its side effects have been put into 3 categories: 1) excess of estrogens: nausea, retention of liquids, uterine cramps, leiomyomas, adenosis of the breasts; 2) excess of gestagens: anabolic weight increase, depressions, frigidity; and 3) defect of the estrogens: atrophy of the mucous membrane, dyspareunia. Intervention in the process of implantation of the ovum with the help of large doses of estrogens (50 mg/day for 4-6 days) presents the problem of determining the ovulation date. Further experiments with immunization against sperm have no practical value, since the increase of amounts of antibiotics in the circulatory system of animals does not necessarily affect the genitals.