While differences in acceptability of steroidal contraceptives from nation to nation are generally recognized, variations in safety and effectiveness have been given little attention. Cardiovascular hazards such as thromboembolic disease, myocardial infarction, and stroke, which create such concern in developed countries, may be insignificant problems in other parts of the world where these diseases are rare in women of reproductive age. On the other hand, the influence of nutritional deficiencies, anemia, intestinal parasitism, malaria, and other widespread health problems on the effects and/or metabolism of steroids, which may be of major concern in developing countries, is just coming under study. Side effects also vary greatly among religiously and ethnically different populations, and significant differences in pregnancy protection and bleeding patterns among different populations have been reported-even with injectables. It is, therefore, important to examine and define intergroup differences and especially to recognize that safety concerns in one geographic setting cannot be automatically assumed to apply equally in other areas.