ObjectiveElectroconvulsive therapy (ECT) is used in the treatment of many psychiatric diseases and this therapy may be effective on antioxidant defence system. In this study, we aimed to evaluate the effects of ECT on oxidative stress.MethodsFourteen major depression, 11 schizophrenia and 8 bipolar affective disorder patients diagnosed and received ECT treatment, and 37 healthy volunteers enrolled in the study. ECT was applied to all patients. Before ECT, after the first and last ECTs, serum samples were obtained. Serum total antioxidant status (TAS), total oxidant status (TOS), and calculated oxidative stress index (OSI) were measured in patients before and after ECTs.ResultsTOS values before ECT were higher in major depression (p=0.005) and schizophrenia (p=0.001) groups compared to the control group. TAS values were lower in major depression (p=0.0001), schizophrenia (p=0.004), bipolar affective disorder (p=0.004) groups compared to the controls. Also OSI values were higher in major depression (p=0.0001), schizophrenia (p=0.001), bipolar affective disorder (p=0.009) groups compared to healthy group. After the last ECT, TOS values were significantly lower compared to TOS values before ECT in major depression (p=0.004) and schizophrenia patients (p=0.004). TAS values after the first ECT were higher compared to values before ECT in major depression patients (p=0.004). After last ECT, OSI values were significantly lower compared to before ECT in schizophrenia patients (p=0.006).ConclusionAs a result, it can be said that ECT did not increase oxidative stress. However, further studies with more patients are needed.