OBJECTIVES: To present the outcomes associated with olanzapine treatment of schizophrenia patients participating in the Olanzapine Post Marketing Surveillance in Japan (OPMS-J), and to compare the maintenance rate of olanzapine in the OPMS-J with that of typical and atypical antipsychotic medication in the Schizophrenia Outpatient Health Outcomes (SOHO) study. METHODS: The OPMS-J is 12-month, prospective, observational study of the health outcomes associated with olanzapine treatment in Japan. Patient enrollment started before November 2003, and completed by July 2004. A total of 1955 out/in-patients were enrolled in the OPMS-J, of whom 1849 were considered as qualified subjects for the analysis of effectiveness. Four types of outcomes were measured in the study: social activity (social activity was assessed using single-item questions that asked whether the patient was involved in any social interactions in the previous 4 weeks), EQ-5D, Clinical Global Impression-Schizophrenia scale (CGI-SCH) and the maintenance rate of olanzapine. Regarding the maintenance rate of olanzapine, the OPMS-J was compared with the SOHO study, as an external control, with typical and atypical antipsychotic medication including olanzapine. RESULTS: The three outcomes, i.e., social activity, EQ-5D and the CGI-SCH, all, significantly improved when the scores at the baseline were statistically compared with those at the endpoint of 12-month follow-up or the end of the surveillance (p<0.001). Also, the deterioration rate of patients status was observed as less than 5 % in the group measured with the CGI-SCH. The maintenance rate of olanzapine in the OPMS-J was 68.25 % (n=1262) in the 12-month follow-up duration, which is similar to that of SOHO study reported at the 12-month endpoint, ranging from 79.5% to 51.4%. CONCLUSION: The improvement of patient-reported outcomes with respect to olanzapine was confirmed in the OPMS-J, a post marketing surveillance in Japan. Also, the maintenance rate of olanzapine in Japan was similar as that in the European study.