Evidence suggests that cesarean birth rates are high and increasing in some developing countries. The objectives of this study are to compile the best current estimate of cesarean birth rates for developing countries, to estimate regional rates, and to document trends nationally and by urban/ rural residence where data permit. A database of cesarean birth rates was compiled representing 90 percent of births in the developing world, resulting in an estimated cesarean birth rate for the developing world of 12 percent, with regional rates ranging from 3 to 26 percent. Data representing 45 percent of births in the developing world show that a majority of countries experienced increases in cesarean birth rates during the 1990s, except in sub-Saharan African countries, where little if any change occurred. Cesarean birth rates must be monitored routinely to call attention to rapidly changing practices. These data can, in turn, trigger investigation into the appropriateness of the rate in a given context.