Rapidly increasing urbanisation, fragmentation of health services, and civil unrest can constitute threats to the efficiency of the excellent immunisation services developed in most South African cities. Among children attending hospital outpatient departments are many who have escaped the net of the preventive services. A system has been developed to immunise all children entering the Red Cross War Memorial Children's Hospital, Cape Town, in whom immunisation is incomplete for age. The Community Health Liaison Group, which co-ordinates these and other health preventive/promotive activities in the hospital, is described.