OBJECTIVE: The authors assessed the association between the catechol-O-methyltransferase (COMT)Val158Met polymorphism and scores on the phobic anxiety scale of the Crown-Crisp Experimental Index. METHOD: A total of 1,234 women completed the Crown-Crisp Experimental Index phobic anxiety scale and were genotyped for the COMT polymorphism. The authors used unconditional logistic regression to compute odds ratios and 95% confidence intervals (CIs) to evaluate the association between the COMT genotype and phobic anxiety. RESULTS: The mean scores for the three genotypes were statistically significantly different. Compared to the COMTMet/Met genotype, the age-adjusted odds ratio for scoring ≥6 compared to scoring 0 or 1 were 1.15 (95% CI=0.71–1.85) and 1.99 (95% CI=1.17–3.40) for the COMTVal/Met and COMTVal/Val genotypes, respectively; a significant gene dosage effect was observed. CONCLUSIONS: Our results suggest that the functional COMT polymorphism is associated with the development of phobic anxiety.