Evaluations of social disability have been found useful in determining factors of diagnostic, therapeutic and prognostic significance in the management of psychogeriatric patients. A random sample of 100 psychogeriatric patients aged 65 or over admitted to three Toronto hospitals were studied prospectively. Standardized clinical and social interview schedules were used to assess patients' mental state, self-care capacity, social isolation, burden on the family and household contribution before admission. These assessments were carried out to determine their significance with respect to diagnosis and outcome. Self-care capacity, as measured by the Activities of Daily Living Performance Test or by informant report, was related to diagnosis and outcome measures in this sample. Social isolation was significantly correlated with length of hospital stay. Burden on the family was not found to be significantly associated with diagnosis or outcome although there was a tendency for patients with organic disorders to present more difficulties for their families. The severe burden imposed on relatives suggests the need for utilization of community social and medical services to provide relief for families of psychogeriatric patients. The implications for management are considered in the light of the above findings.