Objective To explore the status of oxidative stress (OS) in the first-episode schizophrenia patients (FEP) and to examine the effects of antipsychotic drugs on oxidative stress of FEP. Methods The plasma total superox?ide dismutase (T-SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and total antioxidant capacity (T-AOC) were measured in forty-seven FEP (case group) and forty-three healthy volunteers (control group) before and after treatment. Eighteen cases completed 6-week treatment with risperidone (risperidone group) and twenty-five cases completed 6-week treatment with olanzapine (olanzapine group). Results The activity of T-SOD and GSH-Px were lower (P<0.05) and CAT was higher (P<0.05 ) while there was no significant difference in T-AOC (P>0.05) in FEP compared to the control group. Risperidone and olanzapine significantly improved T-SOD and T-AOC, respectively (P<0.05). There was no significant difference between the two groups in the changes of oxidative stress indicators after treatment (P>0.05). Conclusion FEP has alterations of antioxidant enzymes, which may be related to the pathogenesis of schizo?phrenia. Antipsychotics risperidone and olanzapine may improve the oxidative stress in FEP.