Research in mental health has generally used evaluation and outcome measures different from those applied in other medical specialties. We evaluated the utility of a general health measure, the Quality of Well-Being (QWB) scale, in older patients with psychosis. The QWB and standardized rating scales for assessing psychopathology, cognitive impairment, physical comorbidity, and neuroleptic-induced tardive dyskinesia were administered to 85 patients with functional psychoses (mostly schizophrenia or schizoaffective disorder) and 39 normal comparison subjects over age 45. The patients were more impaired than normal comparison subjects on the QWB and other rating scales. The QWB score was affected more by severity of positive symptoms than by any non-psychopathology-related variables. The patients' QWB scores were similar to those of previously studied ambulatory patients with AIDS. Use of the QWB scale may allow direct comparisons of the impact of different psychiatric and physical disorders on the quality of life.