OBJECTIVES: Recently, polymorphisms of several serotonin genes have been suggested to be associated with suicide, but the results are still unclear. We examined whether the T102C polymorphisms of the serotonin 2A receptor gene and the G861C polymorphisms of the serotonin 1B receptor gene were associated with suicidal behavior using drug intoxication. METHODS: The subjects were 52 patients who visited emergency room with suicidal behaviors. Fifty controls were selected from healthy volunteers matched for sex and age to the suicide subjects. The polymorphisms were analyzed with TaqMan(R) assay using primers based on previous studies. RESULTS: The T102C polymorphism of the serotonin 2A receptor gene showed no significant difference between the suicidal attempters and controls in both genotype and allele frequency analyses(p=0.179 and p=0.422, respectively). There was no statistically significant difference between the suicidal attempters and the controls in the G861C polymorphism of the serotonin 1B receptor gene and any significant effect of the genotype distributions or the allele frequencies was not observed(p=0.092 and p=0.987, respectively). CONCLUSION: These findings suggest that the T102C polymorphism in serotonin 2A receptor gene and the G861C polymorphism in serotonin 1B receptor gene are not related to the susceptibility to suicide attempts using drugs. To clarify the genetic influences of the serotonergic system on suicidal behavior, the polymorphisms of other candidate genes in the serotonergic system should be studied with larger numbers of subjects.