Interleukin (IL)-6 is a pleiotropic cytokine that has a major role in inflammatory diseases. The results of two recently published clinical trials that used different study designs demonstrated that tocilizumab, a humanized monoclonal antibody that targets the binding of IL-6 to its receptor, improved the clinical and biological signs of disease activity in both rheumatoid arthritis and systemic-onset juvenile idiopathic arthritis. Adverse events included a higher risk of infections, transient elevation of liver aminotransferases, higher cholesterol levels, and a few allergic reactions. Future studies should investigate the long-term efficacy (clinical and structural) and safety of tocilizumab, including its effect on lipid levels.