The catechol-O-methyltransferase (COMT) gene contains a functional polymorphism, Val158Met, that has been found to influence human pain perception, and one study has found that migraine was less likely among those with the Val/Val polymorphism. In the 1995-97 Nord-Trøndelag Health (HUNT) Study, the association between the Val158Met polymorphism and headache was evaluated in a random sample of 2451 individuals. No association between Val158Met polymorphism and migraine was found. Among women, a lower prevalence of non-migrainous headache was found among individuals with the Val/Val genotype than among those with other genotypes (26.2% vs. 33.6%, p = 0.04). That non-migrainous headache was less likely among women with the Val/Val genotype may be an incidental finding, but should be investigated in further studies.