This single arm study will assess the effectiveness of tocilizumab in combination with traditional DMARDs with regard to the clinical improvement in disease activity (achievement of LDAS) after 24 weeks' treatment in patients with active rheumatoid arthritis (RA) who have had an inadequate response to current traditional DMARD and/or anti-TNF therapy. Patients will receive tocilizumab 8mg/kg iv every 4 weeks, in addition to ongoing DMARDs at the stable pre-entry dose prescribed by the physician, for a total of 6 infusions during the regular treatment period and a further 6 infusions during an optional extension phase. The anticipated time on study treatment is 6 to 12 months, and the target sample size is <500 individuals.