The purpose of this study is to evaluate the efficacy of the combination of tacrolimus + methotrexate compared to methotrexate alone in the treatment of the signs and symptoms of rheumatoid arthritis over 6 months in patients with partial response to methotrexate.

This is a Phase III, 6 month randomized, double-blind, placebo controlled multi-center study with a 6 month open-label extension. Patients will be randomized to the tacrolimus + methotrexate arm or the placebo + methotrexate arm in a ratio of 2:1. Patients who complete the 6-month double-blind phase will be eligible to enroll in the open-label phase of the study.

Inclusion Criteria

• Willing to discontinue DMARDs, other than methotrexate
• Has a diagnosis of Rheumatoid Arthritis using American College of Rheumatology Criteria, of at least 6 months duration
• Have been receiving oral or parenteral methotrexate for at least 3 months

Exclusion Criteria

• Has received tacrolimus for any indication
• Has moderate or severe liver disease
• Has a known history of HIV infection
• Has serum creatinine outside the normal range