OBJECTIVE: Research on schizophrenia has tended to ignore patterns and costs of mental health service use in late life. The present study examined the types of mental health services used and their costs for several age-defined cohorts in a large community mental health system. METHOD: The data covered all users of the mental health system included in the San Diego county billing information system in fiscal years 1986 and 1990. Community mental health service use and codes were modeled as a function of patient demographic characteristics, diagnosis, and age. The patients were grouped into the following age categories: 18-29, 30- 44, 45-54, 55-64, 65-74, and > or = 75 years of age. RESULTS: The total costs for schizophrenia were higher than those for other psychiatric disorders, and they were also age dependent. In both fiscal years, the costs of schizophrenia were higher for the youngest and oldest cohorts than for the patients in the 30-65-year range. CONCLUSIONS: The economic burden of late-life schizophrenia to the public mental health system is at least as high as that of schizophrenia in younger adults.