Paliperidone is a new active substance, belonging to the class of atypical antipsychotic, and is the active metabolite of a well-known active substance, risperidone that has been used for the last 3 years. A randomized, double-blind, multicentric, study to evaluate the safety and efficacy of Paliperidone ER compared to Olanzapine in patients with Schizophrenia was conducted in Indian schizophrenic patients. Pharmacokinetic Evaluation in Indian schizophrenic patients randomized to Paliperidone ER was an open label extension, pharmacokinetic (PK) study of previously conducted phase III trial. The doses of paliperidone 3, 6, 9, and 12 mg were administered during the study. Paliperidone concentrations were measured up to 36 hours post dose after administration of paliperidone ER 30 minutes after dinner to the patients who continued the medication after completion of phase III clinical trial. The mean Cmin, Cmax, AUC (tau) for paliperidone ER 3 mg, 6 mg, 9 mg, 12 mg were found to be [6.71 ng/ml, 23.59 ng/ml, 349.50 hr*ng/ml]; [28.88 ng/ml, 57.77 ng/ml, 1040.86 hr*ng/ml]; [17.25 ng/ml, 71.05 ng/ml, 1032.17 hr*ng/ml]; [34.35 ng/ml, 96.75 ng/ml, 1812.40 hr*ng/ml] respectively. Paliperidone ER was very well tolerated during the pharmacokinetics study.