Evidence has accumulated indicating that proinflammatory cytokines play critical roles in the pathogenesis of RA. Recent clinical studies demonstrate that blockade of IL-6 signaling with tocilizumab, a recombinant humanized anti-interleukin-6 receptor antibody, is a new therapeutic option for the treatment of patients with RA refractory to conventional DMARD therapy and anti-TNF-α therapy. This paper discusses possible mechanisms of action, reviews the results of clinical trials, and discusses the place of tocilizumab in RA treatment.