Objective To observe the expression and investigate the significance of suppressor of cytokine signaling (SOCS) in peripheral blood mononuclear cells (PBMC) of experimental autoimmune uveitis (EAU). Methods 100 Lewis rats were immunized with interphotoreceptor retinoid-binding protein (IRBP) to induce EAU animal model, and they were divided into control group and treatment group randomly. The treatment group was administered cyclosporine A 20mg/（kgmiddot;d）after 1 to 28 days of immunization; the control group received saline buffer at equal quantity. All eyes were evaluated by slit-lamp microscopy before and after 7, 14, 21, 28 days of immunization; IL-4，IL-12，IFN-gamma; in the serum were measured by enzyme linked immunosorbent assay(ELISA); the SOCS mRNA and protein level in PBMC were measured by quantitative polymerase chain reaction (q-PCR) and western blot. Results The inflammation was most obvious at 14 days after immunization. The control group showed obvious iridocyclitis; the treatment group showed mild anterior chamber inflammation but no posterior synechia and hypopyon. The highest level of IL-12 and IFN-gamma; were observed at 14 days after immunization, followed by decline to the baseline at 28 days after immunization in control group; the highest level of IL-12 and IFN-gamma; were found at 14 days after immunization in treatment group, but the level was lower than control group obviously. Compared with the level before immunization, there are no differences at other time-point. The concentration of IL-4 decreased indistinctly in control group but increased in treatment group. SOCS1、Both of SOCS1 and SOCS5 increased to the highest level at 14 days after immunization, as 4.05 and 383 times of preimmunization in control group respectively, as 1.15 and 1.16 times in treatment group respectively. The CIS and SOCS3 mRNA increased lightly in two groups and treatment group milder than control group. Marked increased expression of SOCS1 and SOCS5 protein was detected at 7, 14, 21days than preimmunization, both of CIS and SOCS3 protein were significantly increased on 14, 21 days in control group; only SOCS1 protein was significantly increased on 14 days in treatment group and there are no differences at other time-point compared to pre-immunization. Conclusion Up-regulation of SOCS1 and SOCS5 expression maybe related to intensive response of Th1 in the development of EAU. Mild up-regulation of CIS and SOCS3 maybe associated with intensive response of Th2 which against the reaction of Th1 to carry out the dynamic immune balance.