 This 2 arm study will compare 2 treatment strategies based on tocilizumab in combination with methotrexate or placebo in patients with moderate to severe rheumatoid arthritis. Patients receiving methotrexate treatment will be randomized to receive either a tocilizumab 8 mg intravenous iv every 4 weeks methotrexate orally po weekly or b tocilizumab 8 mg iv every 4 weeks placebo po weekly. After the first 24 weeks of blinded treatment, treatment adjustments increase or decrease of treatment intensity may be introduced at intervals, based on response. The anticipated time on study treatment is up to 3 years, and the target sample size is approximately 470 patients. 