In a study of 357 long-stay hospital residents aged 40 years and over, 30% had significant psychiatric disorder, while a retrospective survey of 215 new admissions over a seven-year period to a psychiatric unit for the mentally handicapped revealed that 20% of patients were aged 40 years and over. Both similarities and differences were found in the overall pattern of disorders between the two groups and a non-handicapped population in a comparable age-range.