Adalimumab (Humira) is a recombinant, fully human IgG1 monoclonal antibody that binds specifically to tumor necrosis factor (TNF)-alpha, thereby neutralizing the activity of the cytokine. Subcutaneous adalimumab has been investigated in well designed trials in patients with active rheumatoid arthritis despite treatment with disease-modifying antirheumatic drugs (DMARDs). Patients receiving adalimumab 40mg every other week in combination with methotrexate (Anti-TNF Research Study Program of the Monoclonal Antibody Adalimumab [ARMADA] and DE019 trials) or standard antirheumatic therapy (Safety Trial of Adalimumab in Rheumatoid Arthritis [STAR] trial) for 24-52 weeks had significantly higher American College of Rheumatology (ACR) 20, ACR50, and ACR70 response rates than patients receiving placebo plus methotrexate or standard antirheumatic therapy. In ARMADA, an ACR20 response was achieved in 25%, 52%, and 67% of adalimumab plus methotrexate recipients at weeks 1, 4, and 24, respectively. In ARMADA and DE019, improvements in the individual components of the ACR response were significantly greater with adalimumab 40mg every other week plus methotrexate than with placebo plus methotrexate. Monotherapy with adalimumab 40mg every other week was associated with significantly higher ACR20, ACR50, and ACR70 response rates than placebo, as well as significantly greater improvements in the individual components of the ACR response. ACR responses were sustained with adalimumab according to the results of extension studies in which patients received adalimumab in combination with methotrexate (up to 30 months) or as monotherapy (up to 5 years). In both concomitant therapy and monotherapy trials, adalimumab was associated with significantly greater improvements from baseline in health-related quality of life (HR-QOL) measures than placebo; adalimumab also retarded the radiographic progression of structural joint damage to a significant extent compared with placebo. Adalimumab was generally well tolerated as both concomitant therapy and monotherapy. In ARMADA, there were no significant differences between adalimumab and placebo (in combination with methotrexate) in the incidence of adverse events; however, in STAR, the incidence of injection site reactions, rash, and back pain was significantly higher with adalimumab than with placebo (in combination with standard antirheumatic therapy). No cases of tuberculosis were reported in either trial.In conclusion, subcutaneous adalimumab in combination with methotrexate or standard antirheumatic therapy, or as monotherapy, is effective in the treatment of adults with active rheumatoid arthritis who have had an inadequate response to DMARDs. Adalimumab has a rapid onset of action and sustained efficacy. The drug also retards the progression of structural joint damage, improves HR-QOL, and is generally well tolerated. Thus, adalimumab is a valuable new option for the treatment of DMARD-refractory adult rheumatoid arthritis.