Dopamine D(2) blocking typical antipsychotic drugs are known to change the cerebral perfusion patterns of schizophrenic patients, especially in the frontal cortex and basal ganglia. In recent years atypical antipsychotics such as olanzapine, which have high serotonin 5-HT(2A)/dopamine D(2) occupation ratios, have been shown to be more effective in the treatment of schizophrenia symptoms. The aim of this study was to evaluate the regional cerebral blood flow (rCBF) of the schizophrenic patients treated with olanzapine in a within-subject design. Twenty-four patients with schizophrenia participated as subjects in the study. Each subject was scanned in a medication-free state and after 6 weeks of 10 mg/day fixed dose olanzapine treatment. Despite the clinical improvement seen in the patients, repeated-measures analysis of variance showed that olanzapine produced no significant changes in cortical rCBF after the six-week treatment. This finding indicates that unlike typical antipsychotics olanzapine has no negative effect on cortical cerebral perfusion patterns of schizophrenic patients.