Contraceptive preparations with a high content of estrogen (75 mcg or more) were prohibited in Sweden in 1974 whereupon the number of reported side effects of the pill markedly declined, both relatively and absolutely. The investigation, which compares the side effects reported during the period 1966-70 when the high dose preparation was on sale and 1974-78 after its prohibition. The decrease in the estrogen content took effect at that time. The risks remain, especially an excess morbidity from thromboembolism among women who use pills. While the risk increases with advancing age, the role played by the pill in the genesis of arterial complications is nonetheless slight. The risk of cardiac infarct among pill users who also smoke is not assessed in this material.