The purpose of this study is to compare the efficacy and tolerability of aripiprazole to olanzapine over 26 weeks for the treatment of schizophrenia

Inclusion Criteria:

• Patients with DSM-IV diagnosis of schizophrenia patients in acute relapse
• Treated as outpatients for at least one continuous 3-month period during the past 12 months
• PANSS total score ≥60
• Previously responsive to neuroleptics (other than clozapine)
• Able to give informed consent and comprehend and satisfactorily comply with the protocol requirements

Exclusion Criteria:

• An Axis I (DSM-IV) diagnosis of schizoaffective disorder
• A clinical picture and/or history that was consistent with: (a) Delirium, dementia, amnestic or other cognitive disorders; (b) Bipolar disorder; (c)personality disorder
• Nonresponsive to prior olanzapine therapy
• Likely to require prohibited concomitant therapy
• DSM-IV criteria for any significant substance abuse within the past three months, including addiction to cocaine or alcohol
• Known to be allergic or hypersensitive to study drugs
• Represented a significant risk of committing suicide based on history or mental status exam
• Unstable thyroid pathology and treatment within the past six months
• A history or evidence of a medical condition that would expose the patient to an undue risk
• Clinically significant abnormal laboratory test results (including urine drug screen), vital sign, or ECG findings