The aims of this study are to investigate whether self-reported facial flushing postalcohol consumption (PAC) among subjects with ALDH2*1/*1 can be attributed to ADH2 or ADH3 and whether the prediction of ALDH2 genotype can be improved by examining the combination of flushing and other accompanying reactions of PAC sensitivity. Fifty-eight subjects of Han ancestry in Taiwan were interviewed for alcohol-sensitivity reactions and their blood samples were genotyped for ALDH2, ADH2, and ADH3. For subjects with ALDH2*1/*1 (n = 46), 70% reported to have no flushing PAC and 30% reported flushing PAC. When subjects with ALDH2*1/*1 had ADH2*1/*1 (n = 11), all reported to have no flushing; otherwise, 35% (for ADH2*1/*2, n = 17) and 44% (for ADH2*2/*2, n = 18) reported flushing. For subjects with ALDH2*1/*1 and at least one ADH2*2 allele, the genotype of ADH3 was not associated with self-reported flushing. PAC flushers with ALDH2*1/*1 (50%) were more likely to report nausea than those with ALDH2*1/*2 (8%). The probability of ALDH2*1/*1 given flushing reported was 0.29, while the probability of ALDH2*1/*1 given both flushing and nausea reported was 0.71. The results indicate that self-reported flushing is determined by both ALDH2 and ADH2 and that prediction of ALDH2 genotype on the basis of self-reported flushing and nausea can help identify subjects at increased risk for alcoholism.