Inclusion Criteria:

• Subject has voluntarily signed and dated an informed consent form, approved by an Institutional Review Board (IRB)/Independent Ethics Committee (IEC), prior to any study-specific procedures.
• Subject is 18 years of age or older.

• If female, subject is either not of childbearing potential, defined as postmenopausal for at least 1 year or surgically sterile (bilateral tubal ligation, bilateral oophorectomy or hysterectomy), or is of childbearing potential and practicing one of the following methods of birth control:

  • condoms, sponge, foams, jellies, diaphragm or intrauterine device (IUD).
  • contraceptives (oral or parenteral) for three months prior to study drug administration).
  • a vasectomized partner.
  • total abstinence from sexual intercourse.
• If female, the results of a serum pregnancy test performed at Screening, prior to the first dose of Humira (adalimumab) must be negative.
• Subject has confirmed diagnosis of active rheumatoid arthritis as defined by >= 6 swollen joints and >= 9 tender joints.
• Subject has an Erythrocyte Sedimentation Rate (ESR) of > 20 mm/hr. ESR will be measured using the Westergren method.
• Subject meets the ACR criteria for diagnosis of RA for at least 3 months prior to enrollment and requires to be started in a biologic containing treatment for the first time, and the investigator chooses Humira (adalimumab).
• Subject has had unsatisfactory response or intolerance to one or more prior DMARDS (e.g., hydroxychloroquine, leflunomide, methotrexate, parenteral gold, sulfasalazine, azathioprine or any combination of those).
• Subject will have an evaluation for latent tuberculosis with a tuberculosis skin test done in the screening visit. Subjects who have evidence of prior TB infection should be given prophylaxis in accordance with CDC guidelines.

Exclusion Criteria:

• Subjects who have had prior treatment with cyclophosphamide, chlorambucil or any other Tumor Necrosis Factor (TNF) biologic as etanercept, infliximab, anakinra, abatacept and adalimumab.
• Subjects who have been previously treated with total lymphoid irradiation or anti-CD4 or CAMPATH 1H monoclonal antibodies resulting in persistent CD4 lymphopenia (CD4 lymphocytes <= 500/mm3).
• Subject has had prior treatment with intravenous (IV) immunoglobulin or any investigational agent within 30 days of screening visit.
• Subject has a history of cancer within the past 10 years other than resected basal cell or squamous cell carcinomas of the skin.
• Subject has a history of malignant lymphoma or leukemia regardless of time since diagnosis.
• Subject has a history of or current acute inflammatory joint disease of origin other than RA, e.g., Mixed Connective Tissue Disease (MCTD), Systematic Lupus Erythematosus (SLE), etc.
• Subject has a history of uncontrolled diabetes mellitus, unstable ischemic heart disease, active inflammatory bowel disease, active peptic ulcer disease, recent cerebrovascular accident (CVA) (within 3 months) which, in the opinion of the investigator, would put the subject at risk by participation in the protocol.
• Subject has a history of active tuberculosis or listeriosis, or other active infections suggestive of significant or profound immunosuppression, such as Pneumocystis carinii, aspergillosis or other systemic protozoan or fungal infections.
• Subject has a positive serology for Hepatitis B or Hepatitis C indicating active infection.
• Subject has a history of positive HIV status defined by an ELISA positive test confirmed by a Western blot test and/or PCR.
• Subject has had a persistent or severe infection(s) requiring hospitalization or treatment with IV antibiotics within 30 days, or oral antibiotics within 14 days, prior to enrollment.