Aripiprazole for the Augmentation of Antidepressant Therapy

Inclusion Criteria: * Outpatients, either gender, 20-65 years of age * Patients diagnosed with major depressive disorder as defined by Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), who fulfill both the following criteria: * Having at least one and no more than three inadequate responses of antidepressants * HAM-D17 score ≥ 14 * Willing and able to comply with the study procedure and sign a written informed consent Exclusion Criteria: * Females who are pregnant/lactating or planning to be pregnant * Presence of personality disorder cluster B (dramatic, emotional or erratic disorders) or any psychotic symptomatology in the current depressive episode based on Investigators judgment * History of organic mental disorder within 1 year prior to the screening visit * Acute risk of suicide attempts within 3 months prior to the initiation of study treatment (HAM D-17 score item 3 ≥ 3) * Electroconvulsive therapy (ECT) for current episode * Past exposure to aripiprazole treatment or any investigational product (including drug and invasive medical device) within 4 weeks prior to the initiation of study treatment * History of substance / alcohol abuse within 1 year prior to the screening visit * Patient with any medical or psychotic feature, including the presence of significant abnormal laboratory values, which is considered not suitable for this study by Investigator