IL-6 is a cytokine featuring redundancy and pleiotropic activity. While IL-6 contributes to host defense against acute environmental stress, continuous IL-6 production plays a significant pathological role in various autoimmune and chronic inflammatory diseases. To counter this drawback, tocilizumab, a humanized anti-IL-6 receptor antibody, was developed. Clinical trials have verified the efficacy of tocilizumab for patients with rheumatoid arthritis, Castleman's disease and systemic juvenile idiopathic arthritis, resulting in approval of this innovative biologic for their treatment. Moreover, a considerable number of case reports and pilot studies have indicated the beneficial effects of tocilizumab on other autoimmune and chronic inflammatory diseases. Further clinical studies to evaluate the efficacy and safety of tocilizumab for these diseases are essential.