Proinflammatory Th17 cells and CD4(+)CD25(+) regulatory T (Treg) cells are two newly identified T lymphocyte subsets, which have opposite effects on autoimmunity and inflammation. To assess the Th17/Treg pattern and cytokine microenvironment in peripheral blood of patients with RA, we included 66 RA patients and 20 healthy volunteers. Of all these subjects, peripheral Th17 and Treg frequencies were analyzed by flow cytometry (FCM) and the plasma levels of interleukin (IL)-17, 23, 6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1 were detected by ELISA. The results demonstrated that RA patients revealed an obvious increase in peripheral Th17 frequencies and levels of Th17-related cytokines (IL-17, IL-23, IL-6, TNF-α) while a significant decrease in Treg frequencies and Treg-related cytokine (TGF-β1) levels when compared with healthy people. Our study indicated that development of RA is associated with peripheral Th17/Treg imbalance and characterized by a proinflammatory cytokine microenvironment, which supports continuing generation of Th17 cells.