Introduction Interleukin 6 (IL-6) is one of pro-inflammatory cytokine and is contributed in the pathological function of chronic inflammatory disease and autoimmune disease. Therefore, IL-6 blockade, a humanized anti-IL-6 receptor antibody, tocilizumab was established, which inhibited IL-6 activity both in vitro and in vivo before utilizing clinical therapy. Methods Since 1999, we performed clinical studies against Castleman’s disease (CD), rheumatoid arthritis (RA) and systemic onset of juvenile idiopathic arthritis (sJIA). Results Almost 95% clinical efficacy was obtained by tocilizumab for the patients with CD. Against the patient with sJIA who could not controlled with any previous medicine and TNF-α blockades, tocilizumab therapy showed 90% efficacy assessed by JIA core set. In the case of RA, clinical studies of tocilizumab were performed with 8000. In results, tocilizumab therapy for RA is tolerated and a most effective therapy in sign and symptom and joint event among the biological reagents assessed by ACR or DAS 28 criteria, and Sharp score. Moreover, tocilizumab therapy showed remarkable clinical efficacy without combination of methotrexate. Not only clinical efficacy, but also most of laboratory findings were shown the improving and normalization of such as CRP, SAA, Fib, Hb, CH50, and MMP-3. Conclusion Since IL-6 blockage is effective for CD, RA, and sJIA, other IL-6 contributed chronic inflammatory disease may be targeted diseases of tocilizumab, such as chronic angitis, autoimmune disease, autoinflammatory diseases, inflammatory bowel disease, amyloidosis, Bechget’s disease and so on.