This study investigated current levels and trends between 1975 and 1986 in the rates of cesarean section in 21 countries and of operative vaginal delivery in 14 countries. Sharp differences in national obstetric practice were found, with cesarean rates ranging from a high of 32 (Brazil) to 7 (Czechoslovakia) per 100 hospital deliveries, and operative vaginal rates from 16 (Canada) to 2 (Czechoslovakia) per 100 hospital deliveries. For most countries, rates of cesarean section have risen as operative vaginal rates have fallen, but some important exceptions exist. A comparison of cesarean section rates for two complications of labor and delivery that can be objectively diagnosed, multiple births and breech delivery, demonstrates that cesarean section rates for these complications rose sharply in almost every country from 1980 to 1985. A comparison of 1985 national rates of intervention and measures of birth outcome found no significant relationship between the two. While such ecological comparisons are imperfect at best, this does indicate that low levels of early infant mortality can be achieved in some populations despite a low rate of cesarean deliveries.