Different results were reported about role of IL-10 in depression in various studies.27 In the study by Dhabhar et al. the results showed lower serum IL-10 level in depressed patients as compared to non-depressed patients.39 While Simon et al found increases in serum IL-10 level in depressed patients.40 Our results was similar to Huang et al and O'Brian et al studies which showed no differences in the serum IL-10 level in depressed patients as compared to non-depressed patients.41,42. The gene discussed is IL10; the disease is major depressive disorder.