Rheumatoid arthritis(RA) is a systemic chronic inflammatory disease characterized by destructive polyarthritis. Although its etiology and pathogenesis are still to be elucidated, recent cumulative evidence has suggested both T cells and proinflammatory cytokines (such as tumor necrosis factor(TNF)-alpha, interleukin(IL)-1, IL-6) play pivotal roles in the pathogenesis. Therefore, they are thought to be optimal therapeutic targets. In fact, new therapies targeted to T cells and proinflammatory cytokines using biological agents including monoclonal antibodies have been developed extensively. Among them, anti-proinflammatory cytokine therapies, such as anti-TNF-alpha therapy, have shown an excellent efficacy and some are currently accepted as a new promising therapy for RA. It is expected that further investigation will provide additional insights into cure of RA.