OBJECTIVE: To describe the current knowledge on safety and effectiveness of the tumor necrosis factor (TNF)-alpha antagonists and identify current knowledge/evidence gaps for study by the Agency for Healthcare Research and Quality (AHRQ) Effective Health Care Program. BACKGROUND: Evidence-based Practice Centers (EPCs) and the Developing Evidence to Inform Decisions about Effectiveness (DEcIDE) network of AHRQ's Effective Health Care Program will study the safety and effectiveness of biologic and nonbiologic disease-modifying antirheumatic drugs (e.g., TNF-alpha antagonists). The current knowledge of safety and effectiveness of TNF-a antagonists is reviewed. SUMMARY: Treatment of adult rheumatoid arthritis (RA) involves determining which agents are safe, effective, and cost effective for an individual. Each individual patient's health system may also play a role in which agents are chosen. Many agents are available for the management of RA, some with high cost and unknown safety. Section 1013 of the Medicare Modernization Act of 2003 authorizes AHRQ to study comparative effectiveness and safety of RA, treatments through both EPCs and DEcIDE centers to develop scientific knowledge for RA management as well as through epidemiologic studies. Results will be compiled through a Clinical Decisions and Communications Science Center, then disseminated to all appropriate stakeholders, including patients, payers, and health care professionals. The current knowledge of safety and effectiveness of TNF-alpha antagonists in the treatment of RA is reviewed. Increased rates of serious infections, including Mycobacterium tuberculosis (MTB), or tuberculosis reactivation, may occur with the use of TNF-alpha antagonists. It is still unclear if RA increases the risk of developing cancer, or if use of TNF-alpha antagonists increases cancer risk. CONCLUSIONS: TNF-alpha antagonists are costly, yet effective treatments for early and late RA. Use of these agents provides rapid relief of RA symptoms and provides positive outcomes, defined as improvements in American College of Rheumatology 20, 50, 70 scores; Health Assessment Questionnaire ratings; activities of daily living; joint space narrowing; erosions; and acute-phase reactants. Reactivation of latent MTB or onset of other infections or cancers may occur in RA patients with TNF-alpha antagonists.