Tumor necrosis factor alpha (TNF-α) is a homotrimeric protein encoded within the major histocompatibility complex (MHC). TNF-α can bind its receptors in the body to play a role in immune regulation and to participate in the various pathophysiology processes including fever, inflammation, infection, wound healing and tumors necrosis. TNF-α, an important component of inflammatory pathways, is up-regulated in the synovial tissue, synovial fluid and serum of rheumatoid arthritis (RA) patients. In RA patients, TNF-α along with many kinds of tissue factors and matrix proteins together promotes the inflammatory response, abnormal apoptosis of synovial cells, pannus formation and cartilage and bone destruction, which maintain the sustainability of the progress of RA. Thus, TNF-α may be a clinical indicator of RA activity as well as an effective target for RA.