Describes in detail the methodology used by the Australian Institute of Health and Welfare to measure health services use and expenditure for specific diseases and disease groups in Australia in 1993-94. A companion report, Health System Costs of Diseases and Injury in Australia 1993-94, provides estimates of the health system costs for each disease and injury group and area of expenditure. Other reports will provide detailed estimates for specific National Health Priority Areas - cancer, cardiovascular disease, injury, mental health and diabetes