The effects that mentally ill people have on their families have been more commented upon than studied. The currently favoured practice of community care has increased the need for a systematic attempt to evaluate the families' problems, and an opportunity to do this occurred when a community psychiatric service was introduced in Chichester in 1958, while the neighbouring Salisbury district continued with a conventional hospital-based service. The Medical Research Council's Clinical Psychiatry Research Unit has been evaluating the new service to find out how it affects referral and admission rates; how it influences social and clinical outcome, and the effect it has on the community itself. As the patient's family is the sector of the community most closely concerned in any extension of the extra-mural care of patients, we began by assessing the effects on them. The present paper therefore describes the assessments we made of the burden the patients' families carried in the Chichester Community Care Service and compares their burden with that experienced by families in Salisbury, where admission to hospital was more commonly practised. The comparison is made in terms of the relief that was afforded the two groups of families over a period of two years.