Abstract Our lab has previously shown that Interleukin (IL)-6- dependent production of autoantibodies against aquaporin 4 in plasmablasts may play a central role in the pathogenesis of neuromyelitis optica (NMO). In this study, we explored the efficacy of tocilizumab, a humanized antibody against IL-6 receptor, in intractable cases of NMO. Eight NMO patients who were unresponsive to current treatments received monthly injections of tocilizumab for at least one year. Tocilizumab significantly reduced the annual relapse rate, neurogenic pain, and fatigue in NMO patients. These results indicate that IL-6 signaling plays a crucial role in the pathogenesis of NMO and highlight the value of IL-6 receptor inhibition for the treatment of NMO.