BACKGROUND: Little is known about socioeconomic differences in access to life-saving obstetric surgery, yet access to a caesarean for women is essential to achieve low levels of maternal mortality. We examined population-based caesarean rates by socioeconomic groups in various developing countries. METHODS: We used data from 42 Demographic and Health Surveys in sub-Saharan Africa, south and southeast Asia, and Latin America and the Caribbean. We report caesarean rates by wealth quintile and the absolute and relative difference between the richest and poorest quintiles. We also categorise the sample into richer and poorer halves and examine caesarean rates within rural areas. FINDINGS: Caesarean rates were extremely low among the very poor: they were below 1% for the poorest 20% of the population in 20 countries and were below 1% for 80% of the population in six countries. Only in five countries did the very poor have caesarean rates exceeding 5%. At the other extreme are seven countries, mostly in Latin America, where caesareans are far in excess of the suggested maximum threshold of 15% for at least 40% of the population. INTERPRETATION: In the poorest countries-mostly in sub-Saharan Africa-large segments of the population have almost no access to potentially life-saving caesareans, whereas in some mid-income countries more than half the population has rates in excess of medical need. These data deserve the immediate attention of policymakers at national and international levels.