Background: Polycystic ovary syndrome (PCOS) is considered as the most common cause of female infertility that affects 4-10% of women in the reproductive age. Previous studies have shown the role of a balanced immune response in a successful pregnancy and fertility. Objective: To investigate the T helper cells type 1 (Th1) /Th2/Th17/Treg paradigms in peripheral blood of infertile PCOS compared with normal fertile women. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated at the late follicular phase from 10 PCOS and 10 fertile women. PBMCs were stimulated with PMA and ionomycin in the presence of Berefeldin A as Golgi stop agent to detect intracellular cytokine production (IFN-γ , IL-17, and IL-4) from CD3+CD4+T cells population indicating T helper (Th) cells subsets by flowcytometry. Moreover, regulatory T cells were enumerated using CD25 and Foxp3 markers. Results: In this study, we report that the frequency of Th1 cells was increased compared to Th2 cells in infertile PCOS when considering Th1/Th2 ratio (P=0. 05). Analysis of Th17/Th2 ratio showed a significant difference with a bias toward Th17 dominancy in PCOS (P=0. 02). The proportion of CD4+CD25+Foxp3+ regulatory T cells was significantly lower in PCOS patients than that of healthy fertile women (P=0. 02). Conclusion: In summary, Th1 and Th17 bias and reduction of Treg and Th2 cells as regulators of immune responses might be involved in the pathogenesis of PCOS. These results are suggestive of an altered immune response to inflammatory status in PCOS patients, likely causing some complications such as infertility in these patients.