Aggression is associated with the 'low' activity allele (Met) of the functional Val158Met polymorphism among people with schizophrenia spectrum disorders relative to the 'high' activity (Val) allele. We examined this polymorphism in a sample of 112 people with axis II personality disorders. Participants completed the Buss Durkee Hostility Inventory. Two single nucleotide polymorphisms in the COMT gene were genotyped in these participants classified as 'white' according to US Census Bureau definitions. We failed to observe an association between the Val158Met allele and aggression but observed an association between self-reported aggression and the G allele of a biallelic polymorphism located in the 3'' UTR (rs16559). This allele is less prevalent among schizophrenics and is associated with lower COMT expression in the brain. These findings provide limited support for a role of COMT in modulating aggressive behavior, and are extended to people with personality disorders.