The purpose of this study is to determine the efficacy (effectiveness) and safety of paliperidone ER compared with placebo in the prevention of recurrence of symptoms of schizophrenia.

Paliperidone ER is currently being investigated as treatment for the acute symptoms of schizophrenia and also as maintenance treatment. This trial is designed to evaluate efficacy and safety of paliperidone ER in prevention of recurrence of psychotic symptoms in patients with schizophrenia. This trial is a randomized (patients will be assigned to different treatment groups based solely on chance), double-blind (neither the patient nor the physician will know if placebo or drug is being given and at what dose), placebo-controlled, parallel-group, multicenter study consisting of 5 phases: a screening phase of up to 5 days; a 8-week open-label run-in phase, during which all patients will be treated with open-label, flexibly dosed paliperidone ER (3 to 15 mg) orally once daily to identify a dose that will achieve control of their acute psychotic symptoms (only patients who maintain a stable dosage regimen and have a total Positive and Negative Syndrome Scale [PANSS] score \

Inclusion Criteria:

• DSM-IV diagnosis of schizophrenia at least 1 year before screening
• experiencing an acute schizophrenic episode with a total PANSS score between 70 and 120
• agree to be hospitalized for a minimum of 14 days at the start of the study
• capable of administering study medication themselves or have assistance with study medication administration consistently available throughout the study
• resided at the same address continuously for at least 30 days prior to screening
• able and willing to fill out self administered questionnaires
• washout of antiparkinsonian medications, beta-blockers
• antiepileptics, lithium 3 days prior to the start of the run-in phase

Exclusion Criteria:

• DSM-IV Axis I diagnosis other than schizophrenia
• DSM-IV diagnosis of substance dependence within 6 months prior to screening (nicotine and caffeine dependence are not exclusionary)
• preexisting severe gastrointestinal narrowing (pathologic or iatrogenic)
• injection of a depot antipsychotic within 120 days before screening, or use of paliperidone palmitate within 10 months before screening
• previous history of lack of response to risperidone when acutely psychotic
• history of neuroleptic malignant syndrome
• significant risk of suicidal or violent behavior