The purpose of this study is changing (improving), after initiating various doses of Paliperidone ER on schizophrenia patients.

In this study, investigators are going to examine the effectiveness of Paliperidone ER on depressive symptoms toward schizophrenia patients who are previously unresponsive to other oral antipsychotics. In addition, the relationship between the change of depressive symptoms and adherence will be studied. Even though this study has a limitation of being designed as an open-labelled clinical study, it would be useful for clinicians because this study examines the influences toward adherence related to various factors and the changes of depressive symptoms related to switching to Paliperidone ER, which is well-proven medication.

Inclusion Criteria:

• Age: 18 ~ 65
• Patient with schizophrenia according to DSM-IV criteria
• Patient have signed on the informed consent, and well understood the objective and procedure of this study.
• Patient who need initiation of new antipsychotics due to newly-development or recurrence of acute psychosis
• MADRS≥16
• Competent patient who is manage to answer the questionnaires.
• In case of female at child-bearing age, consent to use appropriate contraceptive methods(oral pill, contraceptive injection, intrauterine device, double barrier method and contraceptive patch) during entire duration of this study.

Exclusion Criteria:

• Past history of NMS.
• Allergy or hypersensitivity to Risperidone or Paliperidone ER.
• History of using clozapine within 1 month before screening.
• Initiating or dose-changing of SSRI, MAOI, TCA within 2 months(maintenance is allowed if those have been stable for at least 30days prior to study entry and would not be any dose changes during the study).
• Initiating of Lithium, Valproic acid, Carbamazepine, Topiramate, Lamotrigine or other mood stabilizer within 2months (maintenance is allowed).
• Patient who is supposed to be impossible to participate to this study due to clinical risk of suicide or aggressive behavior based on clinician's opinion.
• History of severe gastrointestinal obstruction(pathologic or iatrogenic) or incapacity to swallow the drug form(it is not allowed to chew, divide, dissolve or make powder of clinical trial medication due to the possibility of influence on pharmacokinetics)
• Current substance dependence(DSM-IV) or past history of dependence (more than 6months)
• Significant biochemical or hematological abnormality or abnormal finding of urinalysis, based on clinician's opinion.
• History of cardiac disease which predispose to QT prolongation(sick sinus, complete AV block, CHF, ventricular tachycardia, hypokalemia or hypocalcemia) or current medication of QT prolonging drugs
• Patients who take QT prolonging drugs or have
• Pregnant or breast-feeding female patient.
• History of participating to other investigational drug trial within 1month prior to screening.
• History of taking of long-acting antipsychotics injection within 3month before screening.
• Investigator or employee at clinical trial center, personnel related to investigator or trial center on this or other study, or family of employee or investigator