A total of 219 inpatients with a DSM-III diagnosis of major depression, 150 women and 69 men, were followed prospectively for 3-10 years and mortality was recorded. The patients were previous participants in psychopharmacological multicenter trials, which were carried out for the purpose of comparing the antidepressant effect of newer 5-HT reuptake inhibitors with that of the tricyclic antidepressant drug, clomipramine. The study comprised patients with a total Hamilton Rating Scale for Depression score of > or = 18 and/or a Hamilton subscale score of > or = 9. Diagnostic classification according to the Newcastle I Scale in endogenous and nonendogenous depression was performed. The observed mortality was significantly greater than that expected. The increased mortality was essentially due to suicides and mainly found among women. Patients scored as nonendogenously depressed had a significantly higher suicide rate than endogenously depressed patients. The excess number of suicides in the nonendogenous group largely occurred within the first year of observation. No association was found between response to the antidepressant treatment in the trial and the suicide risk in the first 3 years of observation.