To collect data at an international level on the use of medical care and its relation to characteristics of both the population and the prevailing health care systems. Variables Questions covered the following areas: Psychosocial and demographic characteristics, e.g. health related attitudes, family composition, income, education and locus of responsibility for health within the family. Levels of ill-health and perceived morbidity, reasons for use of health services, e.g. restricted activity days, bed disability days, chronic illness and disability, selected indicator conditions of pyschobiological dysfunction, and dental and vision problems. Use of health services provided by physicians, hospitals, dentists, and selected categories of non-physician health care personnel, and use of prescribed and non-prescribed medicines.