Abstract: Objective To investigate the effect of leflunomide on the inflammatory factors and immune function of rats with chronic glomerulonephritis. Methods Thirty rats of chronic glomerular nephritis model were established by injecting cationic bovine serum albumin (C-BSA). Rats with successfully modeled were randomly divided into model group and observation group. Another 15 rats injected with physiological saline in the same way were chosen as the control group. Modeling after 2 weeks, rats in the observation group were given leflunomide meters suspension by gavage treatment with 5 mg/(kg·d). Rats in the control group and model group were given equal volume of saline. Rats were killed after continuous intragastric for 4 weeks. The levels of serum creatinine, blood urea nitrogen, serum total cholesterol, serum albumin and 24 h urine protein were recorded. mRNA and protein levels of peripheral blood tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were detected by RT-PCR and ELISA method. Peripheral blood T lymphocyte subsets were evaluated by flow cytometry (FCM). Results Compared with the control group, the levels of serum creatinine, blood urea nitrogen, serum total cholesterol, serum albumin and 24 h urine protein in model group and observation group were significantly increased ( P<0.05); Compared with the model group, these biochemical indexes in observation group decreased significantly ( P<0.05). Comparison with the control group, mRNA and protein levels of peripheral blood TNF-α and IL-6 in model group and observation group rats were significantly increased ( P<0.05). Compared with the model group, mRNA and protein levels of TNF-α and IL-6 were significantly decreased ( P<0.05). Compared with the control group, peripheral blood T lymphocyte subsets in the model group and observation group were imbalance, the difference was significant ( P<0.05). Compared with the model rats, T lymphocyte subsets in the observation group after treatment tended to be stable ( P>0.05). Conclusion Leflunomide can significantly reduce the levels of biochemical indexes and inhibit the inflammatory reaction. The mechanism may be related to the regulation of immune function.