Preeclampsia and eclampsia continue to be among the leading causes of maternal death. However, national estimates of the occurrence of these conditions have not been available. To derive national rates of preeclampsia and eclampsia and to characterize the women at highest risk of the development of these conditions, we analyzed data from the National Hospital Discharge Survey for the years 1979 through 1986. We found that 26 per 1000 births during this period were complicated by preeclampsia and 0.56 per 1000 births were complicated by eclampsia. The rate of mild or unspecified preeclampsia remained constant over the study period. In contrast, the rate of severe preeclampsia increased sharply and the rate of eclampsia declined by 36%. Maternal age less than 20 years old was the strongest risk factor for both preeclampsia and eclampsia. These data indicate a need for improved prenatal care among teenagers.