OBJECTIVE: Previous studies in schizophrenia have identified abnormalities involving the basal ganglia, but the contribution of neuroleptics to the motor system abnormalities in schizophrenia is usually a confounding factor. This study addressed the issue of whether parkinsonism, a reflection of dopaminergic hypofunction, occurs in schizophrenia per se. METHOD: Clinical ratings and quantitative instrumental measures of parkinsonian rigidity, tremor, and bradykinesia were obtained in 24 neuroleptic-naive schizophrenic patients and 24 age- and gender-matched comparison subjects. RESULTS: According to the clinical ratings, 21% of the schizophrenic patients had rigidity and 12% had bradykinesia, in contrast to none of the normal comparison subjects. With the use of instrumental measures, rigidity and tremor were observed in 29% and 37%, respectively, of the schizophrenic patients, compared to 4% and none in the normal comparison group. The schizophrenic patients also exhibited greater right-side than left-side parkinsonism. CONCLUSIONS: The findings suggest that extrapyramidal motor signs may be part of schizophrenia proper and that some patients with schizophrenia have left striatal hypodopaminergia unrelated to neuroleptic treatment.