Adalimumab is a recombinant human immunoglobulin G1 monoclonal antibody that is specific for human tumor necrosis factor. Based on the data presented in this article, adalimumab administered alone or in patients partially responsive to methotrexate exhibits a rapid onset of action, provides a substantial reduction in signs and symptoms, and results in an improvement in physical function and health-related quality of life. Adalimumab has been demonstrated to inhibit progression of structural joint damage in patients who have long-standing rheumatoid arthritis. Taken together, the data support adalimumab as a new therapeutic option for patients with moderate to severe rheumatoid arthritis.