BACKGROUND: Serotonin transporter gene-linked polymorphism region(5-HTTLPR) and catechol-O-methyltransferase(COMT) genes are thought to be important factors in some personality traits and the etiology of anxiety disorder. The goal of this study was to determine the role of these genes in personality traits. METHOD: The participants included 116 healthy adults with no history of psychiatric disorders and other physical illness for the last 6 months. All participants were tested by Temperament and Character Inventory(TCI). The 5-HTTLPR, COMT val158met gene polymorphisms were analyzed with PCR(Polymerase Chain Reaction). Differences on TCI dimensions and sub-scales among groups were examined with t-test and ANOVA. RESULT: There were possible relationships of the 5-HTTLPR with self-transcendence(P=0.050) and COMT val158met polymorphism with cooperativeness(P=0.053). CONCLUSION: We found associations between 5-HTTLPR, COMT polymorphisms and the some TCI character dimensions. Further studies of polymorphisms of other genes and their interactions may clarify the complex relationship between personality and genes.