The aim of this study was to evaluate the relations of childhood trauma (CT) and obsessive-compulsive (OC) symptom dimensions to suicide ideation in patients with obsessive-compulsive disorder (OCD). Seventy OCD outpatients with lifetime suicide attempts and 60 controls were included. Participants completed the Scale for Suicide Ideation (SSI), the Childhood Trauma Questionnaire-Short Form (CTQ-SF), the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Dimensional Obsessive-Compulsive Scale (DOCS) and the Depression Anxiety Stress Scales (DASS-21). Among OCD patients, 97.1% had current suicide ideation. OCD patients revealed higher scores on CT, suicide ideation, depression and anxiety than controls. The CT history of sexual abuse (SA) and OC symptom dimension of unacceptable thoughts explained suicide ideation. It was concluded that SA and unacceptable thoughts may contribute to high suicidality and have important implications for the assessment and treatment of suicide risk in OCD patients with lifetime suicide attempts.