Tocilizumab (RoActemra or Actemra) is a recombinant humanized monoclonal antibody that acts as an interleukin (IL)-6 receptor antagonist. Intravenous tocilizumab 8 mg/kg (and no less than 4.8 mg), in combination with methotrexate, is approved in the EU for the treatment of moderate to severe active rheumatoid arthritis in adult patients with inadequate response to, or who are intolerant of, prior disease-modifying anti-rheumatic drug (DMARD) or tumour necrosis factor (TNF) antagonist therapy. It may also be administered as monotherapy in patients intolerant of methotrexate or in whom methotrexate therapy is inappropriate. Tocilizumab is also approved in Japan for the treatment of polyarticular-course juvenile idiopathic arthritis, systemic-onset juvenile idiopathic arthritis and Castleman's disease. Intravenous tocilizumab was effective and generally well tolerated when administered either as monotherapy or in combination with conventional DMARDs in several well designed clinical studies in adult patients with moderate to severe rheumatoid arthritis. Tocilizumab-based therapy was consistently more effective than placebo, methotrexate or other DMARDs in reducing disease activity, and some trials also showed significant benefits with tocilizumab in terms of reducing structural joint damage and improving health-related quality of life (HR-QOL). Notably, tocilizumab-based therapy was effective in patients with long-standing disease in whom anti-TNF therapy had previously failed. More data are required to determine the comparative efficacy and safety of tocilizumab versus other biological agents and to establish their relative cost effectiveness. However, the present data suggest that tocilizumab is an important emerging treatment option in adult patients with moderate to severe rheumatoid arthritis.