This is a single arm (one group of patients), open-label (all people know the identity of the intervention) multicenter 6-month study. Throughout the study flexible dosing of paliperidone ER in a range of 3 to 12 mg/day may be used. Flexible dosing will allow investigators to adjust the dosage of each patient based on the individual needs. Patients will receive 3, 6, 9 or 12 mg of paliperidone ER once daily for 6 months. The tablets will be taken orally. Adjustment of the dosage will be done at the investigator's discretion, based on the individual patient's clinical response and tolerability to the study drug.