 This randomized, double-blind, placebo-controlled study will use Magnetic Resonance Imaging MRI to assess the efficacy of tocilizumab plus non-biological DMARD in patients with moderate to severe rheumatoid arthritis who have had an inadequate response to non-biological DMARDS. Patients will be randomized to receive either intravenous tocilizumab at 8mgkg minimal dose 480mg, maximum dose 800mg or placebo every 4 weeks, in addition to their stable dose of non-biological DMARD. Anticipated time on study treatment is 24 weeks, and target sample size is 100. 