This is a multi-center, double-blind, placebo-controlled, parallel-group, randomized trial of HuMax-CD4 in the treatment of patients with active rheumatoid arthritis (RA) who have failed treatment with Methotrexate (MTX) and at least one TNF-alpha blocking agent. Patients are randomized to receive one of two doses of HuMax-CD4 or placebo. The drug will be administered as a subcutaneous infusion (given just under the skin), more often in the beginning and then followed by a maintenance dose. There is a 4 week follow up period, and the final evaluation of the clinical endpoints takes place 26 weeks after treatment start. The trial lasts about 28 weeks in all.