To evaluate clinical efficacy and tolerability of MRA, patients with RA are randomized to receive either MRA or conventional DMARDs.

Inclusion criteria

• Diagnosed as having RA, on the basis of the criteria stipulated by the American Conference on Rheumatism (ACR) in 1987.
• With RA that has continued for at least 6 months but less than 5 years, with the date of first appearance being taken as the date of RA diagnosis.
• Active RA despite at least one DMARD or immunosuppressant. Active disease is defined as having at least 6 tender and 6 swollen joints among 49 and 46 joints stipulated by the Japanese Rheumatism Foundation's Drug Evaluation Committee and ESR at least 30 mm/hr and CRP not less than 2.0mg/dL.

Exclusion criteria

• Shown to have class-IV Steinbrocker's functional activity in an evaluation carried out within 4 weeks before administration of the study drug.
• Treated with drugs that delay joint destruction (infliximab, etanercept, leflunomide, etc.) within 3 months before administration of the study drug.
• The oral corticosteroid dose (prednisolone equivalent of up to 10 mg/day)has not been fixed 2 weeks before administration of the study drug.
• Subjected to any of the following within 4 weeks before administration of the study drug: (i) Change in dosage of currently administered DMARDs and/or immunosuppressive agents. (ii) Plasma exchange method. (iii) Surgical treatment (operations, etc.).