The purpose of this international collaborative study was to investigate the prescription patterns of antipsychotic drugs for schizophrenia in East Asia and to analyze factors that affect these patterns. Prescription patterns for patients admitted for treatment of schizophrenia were surveyed using a standardized protocol from six East-Asian region/countries: China, Hong Kong, Japan, Korea, Singapore and Taiwan. Patients' social and clinical characteristics, psychiatric symptoms, course of illness, and adverse effects of medications were systematically assessed and recorded. Prescriptions of the first- and second-generation antipsychotic drugs were compared. A total of 2399 patients were recruited. The second-generation drugs comprised 28.1% of all prescribed antipsychotics, and 46% of the antipsychotic prescriptions were in the context of polypharmacy. The mean dosage of antipsychotics for the whole sample was 675.3 + 645.1 mg chlorpromazine equivalents. Japan had a high frequency of prescribing high doses and polypharmacy; Singapore had a high utilization of depot injections while China had a higher prescription of clozapine. Using multiple logistic regression analysis, distinctions in the prescription patterns of antipsychotic drugs were found: first-generation drugs were mainly for controlling aggressive behavior, while second-generation drugs were targeted at the alleviation of positive, negative psychotic symptoms as well as disruptive behavior in schizophrenia. The present collaborative study highlighted differences in the prescription patterns, especially the under-utilization of second-generation antipsychotic drugs in East Asia. The pattern of antipsychotic medication use varied from country to country and is likely to be influenced by the prevailing health-care system, the availability and cost of the drugs.