Data from a range of well-controlled clinical trials, observational studies, and clinical use support the efficacy of risperidone for both acute and long-term therapy of schizophrenic psychoses. With regard to positive symptoms, the efficacy of risperidone was shown to be at least comparable with that of haloperidol. However, risperidone differs from conventional antipsychotics because it is more effective against the negative symptoms, has beneficial effects on affective and cognitive symptoms, and carries less risk of extrapyramidal side effects (EPS). To date, risperidone is the only atypical antipsychotic to have shown a significantly lower relapse rate compared with haloperidol in a long-term double-blind trial. This review describes comprehensive trial data and therapeutic observations gained with risperidone in the treatment of schizophrenia since its approval.