Background: Although gender differences have been noted in the risk factors for suicide and attempted suicide, comparative studies to date have used only 2 groups and a limited number of measures. The present study compared the effect of gender on suicide among 4 groups of psychiatrically hospitalized adolescents using a cross-sectional design. Methods: The study sample consisted of 404 patients, aged between 12 and 21, who were divided into 4 groups: 76 male suicide attempters, 103 male nonattempters, 143 female suicide attempters, and 82 female nonattempters. Patients were tested for life events, affective disorders, aggression, impulsivity, ego defense mechanisms, and death perception with the Child Suicide Potential Scale, Beck Depression Inventory, State-Trait Anxiety Inventory, Overt Aggression Scale, Multidimensional Anger Inventory, Impulsivity Control Scale, and Life Style Index. Findings were analyzed by multivariate regression with stepwise logistic models. Results: Depression and anxiety were more prevalent in female nonattempters than in male nonattempters; there were no such gender differences among the attempters. Antisocial behavior was more prevalent in male attempters than in female attempters; there were no gender differences on this aspect among the nonattempters. There were gender differences for defense mechanisms in the attempters. Logistic regression models for men and women separately revealed that antisocial behavior and anxiety were common predictors of suicide attempt, that destructiveness was a predictor in women only, and that depression was associated with suicide attempt in men only. Conclusions: Suicide-prone female and male adolescent inpatients show distinct differences in psychopathology, ego defense mechanisms, and life events compared to psychiatrically hospitalized adolescents without any history of suicide attempt. Any deviation from a gender-specific behavior must raise suspicion of a risk of attempted suicide.