To explore the role of parental alcohol consumption in miscarriage we interviewed 80 women who miscarried about their own and their partners' drinking habits. A control group of 81 gestational-age-matched women whose pregnancy ended in the delivery of a healthy infant at term were similarly questioned. The use of alcohol by women and men was equally frequent in both groups. Before pregnancy, the mean alcohol consumption per week had been about 1-2 drinks for the women and 4-5 drinks for the men. During the presumed day of conception, 13% of the women who miscarried and 11% of the women in the control group had drunk on average 3-4 drinks; the other women had been abstinent at this time. Of the partners, 13% and 15%, respectively, had taken a mean of 4-5 drinks. In both groups 58% of the subjects continued to consume alcohol during pregnancy. The mean consumption was about one drink a week by the women who miscarried and half a drink a week in the control group. Of women who miscarried, 36 had a blighted ovum and in this subgroup alcohol consumption in both women and men was similar to that in the other women who miscarried and their partners, suggesting that alcohol is not causally related to the development of a blighted ovum. These results suggest that moderate maternal or paternal alcohol consumption does not increase the risk of miscarriage.