24-week data from a phase IIIb US study have confirmed the safety and tolerability of tocilizumab (either 8 mg/kg alone or 4 mg/kg or 8 mg/kg in combination with nonbiologic DMARDs) for patients with moderate-to-severe rheumatoid arthritis. The adverse event profile of tocilizumab in the 866 patients analysed was similar to previous results, with the most common serious complication being infection.