Case records of 404 elderly patients (aged 65 years or more) who were admitted for the first time to the Psychiatric Hospital in Aarhus were investigated retrospectively. In 315 patients the diagnoses were senile dementia (290.09) and arteriosclerotic dementia (293.09) according to ICD-8. Information about use of psychotropic drugs before admission and on discharge alive was obtained from the patient case records. In the present study, the use of drugs was not found to be correlated with age, sex and degree of dementia. Significantly fewer committed patients were treated with psychoactive drugs and significantly fewer lived independently in their own homes. Only 42 (13%) patients had a crude psychiatric disorder while 251 (80%) were admitted on account of unacceptable behaviour. 90% of the latter group of patients had been treated with one or more psychoactive drugs on admission. The risks involved in the use of psychoactive drugs are discussed. On account of demographic changes in the Danish population and the recent decrease in psychiatric hospital beds and nursing home beds, it is recommended that the patterns of committed admissions of demented patients to psychiatric hospitals should be followed closely.