Serotonergic system dysfunction has been implicated in the etiology of suicide. A large number of genetic studies have focused on the potential involvement of genes coding for components of serotonergic system in suicidal behavior. However, other genes belonging to this system remain to be investigated or have been poorly studied, as is the case of the 5-HT6 receptor (5-HTR6) gene. In this study, we investigated the potential association between the 5-HTR6 gene 267C/T SNP and suicide in a Portuguese population. Blood samples were collected from 179 suicide victims and 189 controls. Genotypes for the 5-HTR6 gene 267C/T SNP were obtained with the restriction enzyme Rsa I. A tendency was found for genotype association between this polymorphism and suicide, but the differences were not statistically significant (chi(2) = 5.37 df = 2, p = 0.068). However, a gender-specific association was detected when comparing the genotype. distribution between mate suicide victims and male controls (chi(2) = 6.988, df = 2, p = 0.030), suggesting that this SNP might have a role in the etiology of suicide in male subjects in the Portuguese population. (C) 2009 Elsevier Ireland Ltd. All rights reserved.