The authors evaluated the safety, tolerability, and efficacy of risperidone in 103 elderly patients (mean age, 71 years) with schizophrenia (75%) or schizoaffective disorder (25%). Using the Extrapyramidal Symptoms Rating Scale (ESRS), Positive and Negative Syndrome Scale (PANSS), and Clinical Global Impression (CGI) scale, they conducted a prospective, open-label, 12-week trial in 14 psychiatric centers in the United States. Patients' symptoms were assessed at baseline and over a 12-week period. At endpoint, ESRS scores were significantly reduced, as were PANSS total and subscale scores. There were no clinically significant changes in electrocardiograms, laboratory test results, or vital signs. Risperidone was well tolerated and efficacious in elderly patients with schizophrenia or schizoaffective disorder.