The authors analyze the use of mental health care resources before and after the initiation of risperidone therapy in patients of Valley Mental Health, an agency providing aggressive community-based treatment in Salt Lake County, Utah. Sixty-three patients were treated with risperidone during the period from February 1994 through June 1995. Data for at least 6 months before (pre-period) and after (post-period) risperidone therapy were available for 61 patients; the mean period for which data were obtained was 31.8 months (pre- plus post-period). Risperidone use was associated with a reduction, albeit nonsignificant, in the numbers of patients requiring acute inpatient hospital care (-29%), days hospitalized (-1 day per year), residential treatment days (-0.7 days per year), and day-treatment visits (-1.7 visits per year), together with small increases, also nonsignificant, in the need for emergency/crisis intervention (0.1 visit per year), outpatient treatment (0.1 visit per year), and case management (2.3 visits per year). The costs of institutional plus ambulatory care declined from $7949 to $6910 per patient per year (-13%); the greatest reduction was in the cost of acute inpatient care (-18%). With the addition of risperidone, the cost of psychotropic medications doubled, resulting in a statistically nonsignificant mean increase in total costs of $305 per patient per year. Among the 36 patients who received risperidone during =<70% of the post-period and the 17 patients who had been hospitalized during the pre-period, total costs declined -3% and -13%, respectively. The results confirm those of previous studies and demonstrate that risperidone can reduce the use of mental health services.