Abstract: OBJECTIVE To investigate the effects of geniposide on Th17/Treg balance and local inflammatory factors in rats with rheumatoid arthritis. METHODS We established the CIA model to observe the histopathological changes of ankle joints in rats. ELISA was used to detect plasma TNF-α， and Western blot was used to detect the protein contents of transcription factor Foxp3 and RORγt. The expression of IL-10 and IL-17 in joint synovial tissue was detected by immunohistochemistry. RESULTS Compared with the normal control group， the serum concentration of TNF-α， IL-17 and ROR-γt and the expression of IL-17 in joint synovial tissue were significantly higher in the model group (P<0.01)， while the concentration of IL-10 and Foxp3 and the expression of IL-10 in joint synovial tissue decreased significantly in the model group (P<0.01). Compared with the model group， the serum concentration of TNF-α， IL-17 and ROR-γt and the expression of IL-17 in joint synovial tissue were significantly lower in the middle- and high-dose groups of geniposide (P<0.05， P<0.01)， while the concentration of IL-10 and Foxp3 and the expression of IL-10 in joint synovial tissue increased significantly in the middle- and high-dose groups of geniposide (P<0.05， P<0.01). CONCLUSION There was an imbalanced Treg/Th17 differentiation in the joint synovium of CIA rats. By inhibiting the differentiation of Th17 cells in joint synovium， geniposide might induce the generation of Treg cells and then restore the Treg/Th17 balance in the diseased area.