The purpose of this study is to evaluate the efficacy and safety of A-prexa compared to Zyprexa in patients with schizophrenia, schizophreniform disorder and schizoaffective disorder.

Inclusion Criteria:

• 20 years to 65 years
• Schizophrenia patient with an acute exacerbation
• Understand the requirement of the study and voluntarily consent to participate in the study

Exclusion Criteria:

• Patients who have another psychiatric disorders
• Patients who have unstable medical conditions
• Patients who have clinically important abnormalities of liver function test (>2.5 fold of upper normal limit), ECG and vital sign at screening visit
• Uncontrolled diabetic patients (plasma glucose level is more than 126 mg/dl in fasting condition)
• Patients who have a history of an allergic reaction to olanzapine
• Patient who have no clinical response to take two or more different atypical anti-psychotics for more than 4 weeks.
• Patient who take clozapine within 12 weeks before screening visit