• The change in total Positive and Negative Syndrome Scale (PANSS) score from baseline to 96 weeks
  

• The change in Clinical Global Impression - Severity (CGI-S) score from baseline to 96 weeks; The change in WHO - Quality of Life and GAF (Global Assessment of Functioning) score from baseline to 96 weeks
  

Although most schizophrenic patients in Korea are currently taking oral antipsychotic medications, it is estimated that up to 75% of them have difficulty in adhering to their daily oral regimen. A long-acting, injectable formulation may eliminate the inconvenience of daily medication. This is a prospective, open-label, single center study to determine the long-term effectiveness and safety of biweekly injections of risperidone microspheres (intramuscular injections of either 25, 37.5, or 50 mg of risperidone, every 2 weeks for 2 years) in schizophrenia patients in Korea, and its influence on their quality of life. The primary measure of effectiveness is the change in total Positive and Negative Syndrome Scale (PANSS) score from baseline to 96 weeks. The study hypothesis is that risperidone microspheres will be effective in the treatment of schizophrenia as measured by the change from baseline in the total Positive and Negative Syndrome Scale (PANSS) score, and with improvements in the quality of life of the patients as measured by the WHO - Quality of Life score and the Global Assessment of Functioning score.

The patients will receive intramuscular injections of either 25, 37.5, or 50 mg of risperidone, every 2 weeks for 2 years.