Study of the problems and requirements of the main caregiver providing home care for dementia patients that have resulted in the patient being institutionalised. To determine the reasons for placing the dementia patient in an institution. Self-administered questionnaire of 48 questions on the patient and caregiver, including a list of complaints, given to the main caregiver. Medical questionnaire on the patient filled in by the geriatrician. Data were collected from 109 questionnaires concerning 75 females with dementia (84.7 +/- 6.7 years) and 34 demented males (80.8 +/- 7.4 years). In two-thirds of cases the main caregiver was a female, aged 61.1 +/- 12.1 years. Cognitive disorders were not the main reasons for institutionalizing patients. The most frequent caregiver complaint at the time of institutionalisation was incontinence, followed by withdrawal. The caregiver's main problem resulting in institutionalisation was dependence, with behavioural disorders in second place. A treatment with anticholinesterase for dementia was associated with a live-in career being provided for 20 months longer than in the case of patients not receiving this treatment. Statistical analysis revealed 6 groups of separate caregiver-patient situations. On the one hand there were those patients who appeared to be easy for the caregiver to cope with: those with no problems, docile patients and passive patients not opposing care. In these cases the caregiver was most often young and male, or not directly related to the patient. On the other hand there were 3 other groups: patients with inappropriate motor behaviours, violent/agitated patients and unmotivated patients who opposed care. These patients lived with an elderly caregiver who had been looking after the patient for several years. Caregivers' requirements are for help with coping with and preventing dependence. The caregiver suffers terribly from a lack of relief, particularly when young. It is necessary to change the focus of home care for dementia patients towards preventing loss of autonomy and its consequences and to allow for periods of relief for home caregivers.