This pilot study is evaluating high dose intravenous methotrexate (500mg/meter square) with leucovorin rescue in the management of patients with severe, active rheumatoid arthritis. Patients must have failed at least one second line agent or high dose corticosteroid therapy to be entered. Methotrexate and leucovorin is given every 2 weeks for a total of 4 doses. Patients are evaluated during this period and for an additional 4 months for changes in arthritis activity and complications related to therapy. The effects of high-dose methotrexate on various measures of lymphocyte function and cell populations in the peripheral blood is studied.