Broken Th17/Treg balance has been reported contributing to several inflammatory autoimmune diseases. The objective of the study was to investigate whether the Th17/Treg balance was impaired in the peripheral blood of patients with rheumatoid arthritis (RA). The frequencies of Treg cells and Th17 cells and mRNA expression of transcription factor RORγt and FoxP3 in peripheral blood of RA patients (n = 37) and healthy controls (n = 30) were determined by flow cytometry and real-time PCR, respectively. Eleven serum cytokines were analyzed by using cytometeric bead array (CBA). The results demonstrated that active RA patients exhibited increased peripheral Th17 cells, Th1- and Th17-related cytokines and RORγt expression while decreased Treg cells and FoxP3 expression. In addition, Th17/Treg ratios were positively correlated with serum concentrations of Th1- and Th17-related cytokines. In conclusion, our results indicated that Th17/Treg balance was broken in peripheral blood, which may play an important role in the development of RA.