It has been established that oral contraceptive formulations used in the 1960s and 1970s increased the risks of myocardial infarction, venous thromboembolism, and stroke. Oral contraceptive formulations have changed, as have prescribing practices, and there was a need for information on the effects of the newer formulations in use. Myocardial infarction is the most important cardiovascular disease in terms of the incidence and mortality attributed to use of oral contraceptives; although the overall incidence of myocardial infarction is relatively low in women of childbearing ages, the incidence is not low in smokers.