Background and Aim : Many studies have shown that these patients have abnormalities in brain waves; therefore, considering the electroencephalographic indices of these patients, it can help to the treatment of these patients and today this is possible by neurofeedback. The main aim of this study was to investigate the effect of neurofeedback with pharmacotherapy for the treatment of OCD patients.Methods : The present study was a single blind randomized clinical trial, which was performed from September 2016 to September 2018 in Farschian Hospital (Sina) in the city of Hamadan. For this purpose, 48 OCD patients were randomly assigned into the three groups: experimental, placebo and control (16 patients in each group). The experimental group received neurofeedback with pharmacotherapy in 25 sessions (3 sessions in week and each session lasted 45 minutes). In the placebo group, the treatment was similar to that of the experimental group, with the difference that the neurofeedback was not actually performed. The control group was only under pharmacotherapy. Five evaluation steps were conducted to investigate the effects of treatments during the study by Yale-Brown Obsessive Compulsive Scale (Y-BOCS), including: before the treatment, session 9 treatment, session 17 treatment, after the end of treatment and 2 months after the end of the treatment. The data were analyzed with repeated measure ANOVA and one-way analysis of variance (ANOVA).Results : The result of repeated measures ANOVA showed that there was a significant trend in the improvement of the total mean Y-BOCS score, the subscale of obsession and compulsions, in the experimental group compared to the placebo and control groups (P 0.01). Also, a step-by-step analysis with one-way ANOVA showed that, this improvement from the third stage to the next had a significant difference in the experimental group compared to other two groups (P 0.05). Moreover, there was no significant difference between the placebo and control groups in any of the variables at different times (P 0.05). Conclusion : The results of the current study showed that the patients undergoing treatment with neurofeedback and pharmacotherapy indicated a significant improvement in reducing the severity of OCD symptoms compared to the other two groups. Therefore, it can be claimed that neurofeedback can be applied as a novel, uncomplicated and non-invasive treatment method as a complementary therapy, along with routine treatments for this disorder.