Forty-four chronic schizophrenic inpatients participated in this multicentre 12-week parallel-group double-blind trial. After a run-in period of 2 weeks and a single-blind placebo wash-out of 1 week, they were randomly assigned to treatment with either the serotonin2 and dopamine-D2 antagonist risperidone or haloperidol. Two patients were excluded from the efficacy analysis. Five patients dropped out in the haloperidol group and 1 in the risperidone group. At the end of the trial, the mean daily dose was 12 mg for risperidone and 10 mg for haloperidol. The risperidone group showed greater improvement on the Positive and Negative Syndrome Scale for Schizophrenia, the Schedule for Affective Disorders and Schizophrenia-change version, and the Nurses' Observation Scale for Inpatient Evaluation. The improvement of negative symptoms was more pronounced in the risperidone group until week 8 of double-blind treatment. The consumption of antiparkinsonian medication was 10 times lower with risperidone. Both drugs were well tolerated and the laboratory, endocrinological and cardiovascular safety parameters were comparable. This study suggests that risperidone is comparable to haloperidol as an antipsychotic, but that it has a safer EPS profile.