have been proven in many studies, but those tackling cytokine in OCD are still limited. The present study aims to evaluate the diagnostic performance of IL-6, IL-10, and the IL-6/IL-10 ratio in the OCD patient group, and to show their correlation with the clinical parameters of OCD. Eighty subjects (60 OCD patients and 20 matched controls) were participating in this study. The enzyme-linked immunosorbent assay was run to quantify the IL-6 and IL-10. Serum IL- 6 exhibited a higher result in OCD patients than controls (p = 0.002) but serum IL-10 levels had no significant difference (p > 0.05). IL-6/IL-10 ratio showed significantly higher values in OCD patients than controls (p < 0.0001). Serum IL-6 and IL-6/IL-10 ratio were negatively correlated with age of onset but were directly correlated with disease duration and disease severity. IL-6/IL-10 ratio showed 86.7% sensitivity and 90% specificity in OCD diagnosis. An immune activation is implicated in the OCD pathogenesis. This was confirmed by the high serum levels of IL-6 in OCD patients. IL-6/IL-10 ratio showed a considerable sensitivity and specificity in the OCD diagnosis. IL-6 and IL-6/IL-10 ratio are correlated positively with the OCD intensity.