We focused on the catechol-O-methyltransferase gene (COMT) and we performed: a review of studies investigating the association between COMT and both suicidal behavior and personality; a meta-analysis of studies investigating the association between suicidal behavior and COMT rs4680 polymorphism; an association study investigating the link between seven COMT polymorphisms (rs737865, rs5844402, rs5993883, rs4680, rs4633, rs165599 and rs9332377) and both personality traits and suicidal behavior.