The goals of this multi-center, open-label study for patients with Rheumatoid Arthritis (RA) are: 1. To evaluate safety and evidence of therapeutic benefit of infliximab and methotrexate (MTX). 2. To evaluate pharmacokinetics (PK) of infliximab and etanercept. 3. To evaluate antibodies to infliximab and etanercept. 4. To evaluate whether switching to infliximab alters progression of structural damage over the study period. 5. To evaluate whether candidate serologic markers correlate with therapeutic response or benefit.

1. To evaluate safety and evidence of therapeutic benefit of infliximab and MTX. 2. To evaluate PK of infliximab and etanercept. 3. To evaluate antibodies to infliximab and etanercept. 4. To evaluate whether switching to infliximab alters progression of structural damage over the study period. 5. To evaluate whether candidate serologic markers correlate with therapeutic response or benefit.

Ages Eligible for Study:  18 Years and above,  Genders Eligible for Study:  Both

Criteria

Inclusion Criteria:

• Have been receiving background MTX for at least 2 months prior to week –4.
• Have been receiving a stable etanercept dose of 25 mg subcutaneously twice weekly for at least 2 months prior to week –4.
• Have shown improvement in signs and symptoms of RA in response to etanercept and MTX according to both the patient and treating physician.
• Have active disease as defined by both a Tender Joint Count (TJC) > 9 (on the 68 joint set) and a Swollen Joint Count (SJC) > 6 (on the 66 joint set).

Exclusion Criteria:

• Have had a serious infection, (e.g. hepatitis, pneumonia, or pyelonephritis), have been hospitalized for an infection, or have been treated with IV antibiotics for an infection within 2 weeks prior to week 0. Less serious infections, (e.g. acute upper respiratory tract infection, or simple urinary tract infection), need not be considered exclusions at the discretion of the investigator.
• Are considered ineligible according to the TB screening, eligibility, assessment, and prevention rules.
• Are participating in another investigative trial (including registry and observational study) while participating in this trial.