OBJECTIVE To assess the efficacy and safety of adalimumab in the treatment of rheumatoid arthritis (RA). METHODS A Cochrane systematic review was performed. The literature search, selection and assessment of the methodological quality of the studies, and the data extraction were performed according to the standard methodology of the Cochrane reviews. Outcome measures included American College of Rheumatology (ACR) and European League Against Rheumatism responses, Disease Activity Score 28 and components of the ACR response, and radiographic and safety data. Weighted mean difference and relative risk were used for reporting continuous and dichotomous data, respectively. Number needed to treat (NNT) or to harm (NNH) were estimated when appropriate. When significant heterogeneity was not found, data were pooled. RESULTS Six studies with 2,390 patients were included in this review. With adalimumab 40 mg every other week (eow) + methotrexate versus placebo + methotrexate, the absolute risk differences to achieve an ACR20, ACR50, and ACR70 response at 52 weeks were 35%, 32%, and 19% with NNT of 2.9, 3.1, and 5.3, respectively. At 52 weeks, adalimumab 40 mg eow and 20 mg every week (ew) significantly slowed the radiological progression. With adalimumab 40 mg eow versus placebo, the absolute risk differences to achieve an ACR20, ACR50, and ACR70 response at 24/26 weeks were 23.64%, 15.31%, and 12.22% with NNT of 5.0, 7.0, and 9.0, respectively. In most of the analyzed studies and comparisons, there were no significant differences in safety outcomes between adalimumab and control groups. CONCLUSIONS On the basis of studies reviewed here, adalimumab is efficacious in the treatment of RA. No serious adverse effects occurred.