<b><i>Background and Aims:</i></b> Literature findings mainly support the notion that suicide attempts (SA) and self-mutilating behavior (SMB) are distinct behaviors, although they may share common psychopathological features. In the present paper we aimed to identify behavioral phenotypes in patients with SA, SMB, or both (SAM) and to analyze the association with candidate genes. <b><i>Methods:</i></b> One hundred forty-two inpatients with a history of SA (n = 86), SMB (n = 22), and SAM (n = 39) were included in this study. Subjects were evaluated using the Tridimensional Personality Questionnaire (TPQ) and the Buss-Durkee Hostility Inventory (BDHI). Polymorphisms within serotonin transporter (SLC6A4, HTTLPR), catechol-O-methyl transferase (COMT, Val158Met), and tryptophan hydroxylase (TPH, 218C>A) were also analyzed. <b><i>Results:</i></b> Principal component factor analysis including the BDHI and TPQ produced 3 factors that could classify the 3 groups of patients with good sensitivity. However, only the ‘pure suicidal' factor had a sufficient positive predictive value. This factor was characterized by high levels of persistence (PS) and, to a lower extent, reward dependence. The distribution of genotypes was not different across patient groups for all polymorphisms, but the SS genotype of HTTLPR was significantly associated with the ‘self-mutilation' factor, characterized by high levels of hostile traits, novelty seeking, and harm avoidance. <b><i>Conclusion:</i></b> The results of the present study suggest that different and overlapping temperamental traits in suicidal and self-mutilating patients are present, although only high levels of PS could predict SA repetition. Finally, HTTLPR may mediate the risk for SMB through modulation of some temperamental traits.