To understand better the epidemiology and to describe the causes of maternal death, we reviewed all identified maternal deaths in the United States and Puerto Rico for 1979-1986. The overall maternal mortality ratio for the period was 9.1 deaths per 100,000 live births. The ratios increased with age and were higher among women of black and other minority races than among white women for all age groups. The causes of death varied for different outcomes of pregnancy; pulmonary embolism was the leading cause of death after a live birth. Unmarried women had a higher risk of death than married women. The risk of death increased with increasing live-birth order, except for primiparas. In order to develop strategies to reduce the risk of maternal death in the United States, future studies should include expanded information about each death, which will allow better understanding of factors associated with maternal mortality.