In a psychological autopsy of 21 children and adolescents aged 11-19 years who committed suicide as compared with a matched-pair control group, 95% of the suicide victims and 48% of the controls had at least one serious diagnosable mental disorder (P less than 0.02). The presence of two or more mental disorders (comorbidity) was the rule occurring in 81% of the suicide victims and 29% of the controls (P less than 0.001). Mood disorders such as major depression, major depression superimposed on dysthymic disorder and dysthymic disorder coexisted with either alcohol and drug abuse, conduct disorder or other mental disorders in 76% of the victims and 24% of the controls (P less than 0.025). The suicide victims experienced significantly more psychosocial stressors and the poorest level of adaptive functioning. This study suggests that suicide in children and adolescents very frequently is the outcome of serious psychiatric disorders, particularly when associated with drug and alcohol abuse.