Tumor necrosis factor (TNF) has been implicated in a number of arthritic disease states, including rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. Adalimumab is the first fully human, high-affinity, recombinant immunoglobulin G 1 (IgG 1) anti-TNF monoclonal antibody. Adalimumab in combination with methotrexate or standard antirheumatic therapies, or as monotherapy, is effective in the treatment of adults with active rheumatoid arthritis who have had an inadequate response to disease-modifying antirheumatic drugs. Adalimumab is also effective in the treatment of patients with moderately to severely active psoriatic arthritis, improving both joint and skin manifestations of the disease as well as disability due to joint damage. In the Adalimumab Trial Evaluating Long-term Efficacy and Safety in Ankylosing Spondylitis (ATLAS), adalimumab significantly reduced the signs and symptoms of active ankylosing spondylitis and established a sustained clinical response in patients who had an inadequate response or intolerance to nonsteroidal antiinflammatory drug therapy. Overall, across these indications, adalimumab demonstrated a rapid onset of action, sustained efficacy with long-term treatment, and was well-tolerated, with few patients discontinuing treatment because of adverse events. The safety profile was similar to other TNF antagonists. Inhibition of TNF activity by adalimumab also significantly improved physical functioning and quality of life measures.