The prevalence of dementia syndromes was studied in individuals aged 70 and over living in institutions integrated into primary care within a limited area in southern Sweden. The populations studied were all persons living in homes for the elderly in the city of Lund (n = 471) and all persons living in nursing homes in the Lund health service district (n = 384). In the former, 30% were moderately demented and 6% severely demented. The corresponding figures for patients in nursing homes were 33% and 36%. Among the various psychiatric symptoms which are common in dementia, confusion was most prevalent. In the homes for the elderly, 32% of the subjects were moderately or severely confused, while the corresponding figure in the nursing homes was 62%. The consumption of sedatives and hypnotics was greater in homes for the elderly than in nursing homes. The presence of moderate or severe dementia was associated with greater use of sedatives and hypnotics in nursing homes. Prevalence studies of this type might be used to study organizational changes in the care of the elderly within a health service district.