Current planning in the field of the community mental health services places considerable emphasis on the after-care of patients discharged from hospital. This is partly in response to the high re-admission rates experienced as a result of the “revolving door” policy, partly to a scepticism about the present state of knowledge regarding factors amenable to primary prevention techniques, and partly to a belief that keeping the patient in the community is in itself beneficial both to the patient and to the community. The benefits of such a policy are felt to lie in avoidance of institutionalization and furthering of rehabilitation, and in preventing a re-distribution of roles within the family to exclude the patient. The primary purpose of the policy is not necessarily to cut short the illness of the patient, at least as measured by time under treatment, and evidence will be given below to suggest that in fact time in treatment is prolonged. This study focusses on one issue. Can aftercare in fact prevent re-admission to hospital to any significant extent? In view of the complex nature of the decision to select which patients are to receive after-care and which not, a factor in itself likely to prejudice any results, successive discharges from a psychiatric hospital falling within selected categories were randomly allocated to psychiatric after-care and to their general practitioner, and followed for a six-month period. A null hypothesis was set up that the re-admission rate during the follow-up period would not significantly differ in the two groups.