Imatinib is a member of a new class of drugs known as signal transduction inhibitors. The purpose of this study is to evaluate the efficacy, safety and tolerability of imatinib in the treatment of rheumatoid arthritis in combination with methotrexate in patients who do not respond satisfactorily to standard treatment, e.g. methotrexate.

Inclusion Criteria:

• With a diagnosis of RA classified by ACR 1987 revised criteria with symptoms for at least 6 months
• Functional status class I, II, III according to the ACR 1991 revised classification criteria
• Patients have to have been treated with MTX at the maximum tolerated dose for at least 3 months, and be on a stable dose and route of administration for at least 2 months prior to study entry
• Disease activity criteria of minimum 6 out of 28 tender and swollen joints at baseline

Exclusion Criteria:

• With current use of DMARDs other than MTX. DMARDs include but are not limited to: biologic agents, thiolates (D-penicillamine, thiopronine), sulfasalazine, gold compounds, antimalarials, cyclosporine A, azathioprine, leflunomide and alkylating agents such as cyclophosphamide
• With any DMRAD treatment used in combination with methotrexate within 1 month prior to study entry. In case of infliximab and leflunomide, a washout period of 2 months is required
• With any therapy by intra-articular injection, including intra-articular corticosteroid use within 1 month prior to study entry

Other protocol-defined inclusion/exclusion criteria may apply.