Objective: To examine the correlation between paliperidone plasma concentration and clinical efficacy in the patients with schizophrenia. Methods:Totally 50 schizophrenia patients were treated by paliperidone. The plasma concentration of paliperidone was monitored by RP-HPLC at the weekend of the 2 nd, 4 th and 6 th week, the clinical efficacy was evaluated using the positive and negative syndrome scale ( PANSS) , and the correlation between paliperidone plasma concentration and clinical efficacy was analyzed. Results:The mean plasma concentration of paliperidone was (31. 89 ± 17. 36) ng·ml-1 at the weekend of the 6th week, and no cor-relation was found between paliperidone plasma concentration and the clinical efficacy (r=0. 146,P=0. 074). Paliperidone plasma concentration in 12 patients with adverse drug reactions (ADR) was higher than that in the patients without ADR [(45. 87 ± 19. 21)ng ·ml-1 vs (27. 06 ± 11. 13) ng·ml-1, P <0. 01]. Conclusion: Paliperidone plasma concentration shows significant individual differences. With the increase of paliperidone plasma concentration, clinical efficacy isn't necessarily improved, while the incidence of ADR may be increased. Therefore, the monitoring of paliperidone plasma concentration is recommended to optimize the therapeutic reg-imen.