OBJECTIVE: To determine whether multivitamin supplements modify the relationship between alcohol consumption during pregnancy and the risk of miscarriage. STUDY DESIGN: We used data from a population-based cohort study of pregnant women (n=1061; response rate=39%). Participants were asked about their alcohol consumption and vitamin intake during pregnancy. RESULTS: Among multivitamin nonusers, women who drank alcohol during their pregnancy were more likely to have a miscarriage compared with women who abstained (adjusted hazard ratio, 1.67; 95% confidence interval, 1.04-2.69). However, among multivitamin users, there was no difference in the risk of miscarriage between alcohol consumers and abstainers. Results suggest the volume of alcohol as well as the timing of multivitamin supplementation may also be important. CONCLUSION: Our findings suggest that a woman of childbearing years might decrease her risk of miscarriage associated with alcohol intake by taking multivitamin supplements. However, our findings should be interpreted with caution and future research replicating these findings is necessary.