PIP: Adverse and beneficial effects, especially with regard to mortality rates, of oral contraceptives (OC) are reviewed. In 1980 approximately 80 million women used OCs worldwide. OCs were first marketed in the United States in the 1960's, but by the 1980's low-dose combination pills with less estrogen and progesterone content became widespread along with the minipill, injectable preparations depo- medroxyprogesterone DMPA, and norethindrone containing capsules. Relative disease risk estimates are based on cohort studies and case- control studies. The Royal College of General Practitioners RCGP Oral Contraceptive Study of 1974 involved 46,000 women aged over 15 (50% were OC users, 50% were nonusers) the Oxford Family Planning Association Contraceptive Study of 1976 recruited 17,032 women aged 25-39, 56% of whom used OCs, and the Walnut Creek Contraceptive Drug Study of 1981 studied 16,638 women aged 18-54 of whom 28% were OC users and 33% were former users. A somewhat elevated mortality among ever-users of OCs in the order of 20% seems to be indicated by these studies mostly attributable to diseases of the circulatory system. Current OC use is also a risk factor in thrombotic stroke of the order of 4 or 5, but former use of OCs lowers the risk to 2. The effect of OC dose and formulation, duration of use, and predisposing factors on hemorrhagic and thrombotic stroke appears to be inconclusive with varying data from different studies. There is evidence for some increase in ischemic heart disease among current OC users, and also a 2-fold increase of myocardial infarction (MI) when smoking, serum cholesterol, and hypertension is taken into account, moreover higher estrogen dosage also contributes to a higher incidence of MI. There is also a 5-fold increase of venous thromboembolism among OC users induced by duration of use and estrogen potency, as OCs seem to promote atherogenesis, although the roles of progesterone and estrogen are conflicting. combination pills reduce the rate of endometrial cancer, provided protection against ovarian cancer, and do not seem to increase breast cancer incidence, although the relative risk of cervical cancer is elevated. Mortality risks with older OCs outweigh the benefits.