To assess the possible adverse effects of maternal epilepsy on the course and outcome of pregnancy, all 138,780 Washington State birth certificates for the years 1980-81 were screened, and 204 births to epileptic mothers were identified. This was a lower than expected frequency of pregnancies in epileptic women. These births were compared with 612 randomly chosen control births for the same 2-year period. Of 46 pre- and perinatal events considered, eight were found to have occurred with significantly increased frequency for mothers with epilepsy. The offspring of these women were 2.8 times more likely to have low birth weight for their gestational age and 2.5 to 3.7 times more likely to have low Apgar scores or asphyxia. The excess risk of these adverse outcomes could not be explained by maternal race, parity, age, previous fetal loss, or socioeconomic status. These findings suggest that increased vigilance for complications of pregnancy and childbirth is warranted for epileptic women.