Although alcohol-related flushing seems to be a genetically influenced protective factor for alcoholism in some Asian groups, little is known about whether this is true for Caucasians. The evidence for alcohol-related flushing as a protective factor for the development of alcoholism was examined in a sample of 5831 Australian twins (2041 men, 3790 women) who were administered a structured psychiatric interview. Twin correlations for self-reported adverse alcohol reactions (e.g., "flushing or blushing" and "feeling very sleepy" after drinking 1 or 2 drinks) were modest, suggesting minimal contribution of genetic factors, but when corrected for reliability of measurement, were consistent with moderate heritabilities. In accord with studies examining Asian samples, we found that individuals who experienced adverse reactions after drinking small amounts of alcohol drank less often and slightly less per drinking occasion than those who did not experience adverse reactions. However, those who experienced adverse reactions were more likely to have symptoms of alcoholism and to report a parental history of alcohol problems. We conclude that self-reported alcohol-related flushing is not a protective factor for alcoholism in Caucasians and may be a risk factor.