The prevalence of mental disorders (DSM-III-R Axes I and II) among adolescent suicide victims (n = 53) was investigated in a nationwide psychological autopsy study in Finland. The data were collected comprehensively through interviews of the victims' relatives and attending health care personnel and from official records. Following independent assessment by two psychiatrists, the DSM-III-R diagnoses were assigned in consensus meetings. A large majority of the victims (94%) suffered from a mental disorder. The most prevalent disorders were depressive disorders (51%) and alcohol abuse or dependence (26%). The prevalence of adjustment disorders (21%) was higher than in most studies from other countries. Personality disorder was diagnosed in 32% of the cases. Comorbidity was found in 51% of the victims. The results indicate a strong relatedness between adolescent suicide and the presence of depression, antisocial behavior, and alcohol abuse.