Previous clinical trials have clearly shown the superiority of olanzapine to haloperidol in the improvement of extrapyramidal symptoms (EPS) in schizophrenic patients. The primary purpose of this study was to compare EPS profiles in Japanese schizophrenic patients treated with an atypical antipsychotic, olanzapine, or a typical antipsychotic, haloperidol, as measured by the Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). The DIEPSS, which consists of eight individual parameters and one global assessment (overall severity), was used to evaluate 182 patients enrolled in this 8-week study. The primary safety analysis was maximum change (that could be either a decrease or increase) from baseline in DIEPSS total score. Secondary analyses included change from baseline to maximum in DIEPSS total score, change from baseline to endpoint (LOCF) in DIEPSS total score, and the rank sum of the maximum change (that could be either a decrease or increase) from baseline in the DIEPSS individual items. Incidence of treatment-emergent EPS adverse events using the DIEPSS scale was also analyzed. The olanzapine group showed statistically significant superiority to the haloperidol group on the primary analysis (p<0.001). Secondary analyses also demonstrated olanzapine's superiority in DIEPSS total, parkinsonism, akathisia and overall severity scores (all p< or =0.014). Categorical analysis of treatment-emergent akathisia and parkinsonism syndromes at endpoint showed improvement in the olanzapine group but worsening in the haloperidol group. The results from this study suggest that olanzapine, as in Caucasian populations, is a safe treatment in Japanese patients chronically ill with schizophrenia.