The prevalence of mental disorders was studied in a representative sample of 85-year-olds living in Gothenburg, Sweden, (n = 494). All subjects were examined by a psychiatrist, whose diagnoses were defined according to the DSM-III-R criteria. In the sample, the prevalence of dementia was 29.8%, and of any other mental disorder was 24.3%. Psychotic disorders were present in 4.7%, depressive disorders in 12.6%, and anxiety disorders in 10.5%. Anxiety disorders were more common in women than in men. Of all subjects, 42.5% used a psychotropic drug (men 30.1%, women 47.6%, p < 0.001), 34.2% used anxiolytic-sedatives, 14.0% used antidepressants, and 5.7% used neuroleptics. Women used significantly more anxiolytic-sedatives and antidepressants than did men. Of those with no mental disorders, 29.1% used a psychotropic drug. Although the prescription of psychotropic drugs was high, only one fifth of those with depressive disorders received antidepressant drug therapy and one tenth of those with psychotic disorders received neuroleptics.