The discussion about the side-effects of oral contraceptives received new aspects through the publication of the prospective British Study "Oral Contraceptives and Health" (by the Royal College of General Practitioners) in 1974. This article is divided into the following sections: Beneficial side-effects (elimination of symptoms in dysmenorrhea, endometriosis, acne vulgaris, menorrhagia and anemia). Harmless side-effects (harmless symptoms not implying illness). Clinically important side-effects (menstrual disorders, facilitation of moniliasis and trichomoniasis, diseases of the circulatory system, thrombo-embolism). Oral contraceptives have no adverse effects on the fertility of women. Significant is the conclusion that pregnancy and children are normal after the use of oral contraceptives. There are no indications of an increased risk of cancer. The results of the British study confirm a reduced incidence of benign breast tumors in women using oral contraceptives. The suggestion to select a pill-type considering the hormonal constitution of a woman did not prove to be of help. The original proposal of changing the pill-type according to the observed side-effects therefore remains valid. A classification of the used oral contraceptives into the groups "with gestagen accentuation", "hormonally balanced" and "with estrogen accentuation" will help the physician to prescribe the most useful type. An extensive table summarizes the most frequent side-effects, explains their causes and recommends ways of eliminating the symptoms by changing the pill-type.