The economic costs of schizophrenia in New South Wales, Australia, were estimated using an incidence-based approach. The incidence of the disease was obtained from a case register. Direct treatment costs were calculated from length of stay data, the probability of readmission, and a direct costing of inpatient and outpatient care. Indirect costs were calculated from tables of average weekly earnings and work-force participation rates modified for the expected types of outcome. The prodrome was costed similarly. Costs were $139 million (in 1975 U.S. dollars), or $29 per head of the population of the State. A sensitivity analysis indicated that the likely margin of error of the estimate was plus or minus 15 percent. Comparison with the costs of myocardial infarction (in the same State at the same time and costed by the same methods) demonstrated that schizophrenia is a costly disease.