Serotonin (5-HT) and 5-hydroxyindoleacetic acid concentrations were determined in various brain areas of nonschizophrenic suicide victims, chronic schizophrenic patients with or without suicide as the cause of death, and normal control subjects without psychiatric or neurologic disorders. Serotonin concentrations in the basal ganglia were significantly elevated in suicide victims and chronic schizophrenic patients, as were 5-hydroxyindoleacetic acid concentrations in the occipital cortex. These differences were not specific to either patient group and may have been caused by neuroleptic or antidepressant treatment. A decreased 5-HT concentration was found in the hypothalamus of nonschizophrenic suicide victims. Among the chronic schizophrenic patients, there was no significant difference in the hypothalamic 5-HT content between the suicide victims and others, indicating that low 5-HT levels in the hypothalamus are not characteristic of schizophrenic patients who died of suicide.