Abstract: Objective To observe the effect of thalidomide on MCP-1 in synovial joints of rats. Methods A CIA model of Wistar rats was established by injecting bovine II collagen（BIIC）. The rats were randomly divided into normal control group,CIA control group,indometacin group and thalidomide group. Results The CIA model was successfully established 11-13 days after injection of BIIC. The swelling of joints reached its peak 17 days after injection of thalidomide and was milder in thalidomide group. Thalidomide significantly ameliorated the symptoms of CIA rats,inhibited swelling of joints,and reduced inflammatory invasion and expression of MCP-1. Conclusion The anti-inflammatory action of thalidomide is related to the expression of MCP-1.