Quality assurance is growing in significance in health care world wide. The European Office of the World Health Organization has included quality assurance in its 38 health-policy targets for health care. Most experience in this field has hitherto been gained in the USA and in the Netherlands. In West Germany, the most extensive step which has been taken to provide quality assurance has been the perinatal study which is a record of approximately 80 per cent of births. Apart from this, there are pilot studies in existence in particular in the areas of surgery, of operative gynecology and of paediatry. Quality assurance in in-patient and out-patient care has been laid down by law in West Germany since 1st January 1989. Using this as a basis, the Institute for Health-Systems Research is acting as advisor for a pilot study ("Pilot Study for Quality Assurance in Hospitals of Schleswig-Holstein") which is at present being carried out in Schleswig-Holstein and in which 12 hospitals are participating. The pilot study is so structured that it has developed methods for measuring quality assurance in the fields of surgery, internal medicine, gynecology and obstetrics, nosocomial infections, haemotherapy and nursing. Quality assurance is a sensitive area. Indications will be given to what should be heeded when introducing measures for quality assurance in hospitals. Institutes with clearly defined functions are required in order to carry out quality assurance.