Background: Rheumatoid arthritis (RA) is an inflammatory disease of the connective tissue with unknown etiology. In most cases its etiopathology is chronic progressive with periodic flares and remissions while its symptoms can vary in different individuals. Pain, stiffness, swelling and functional limitation increasingly constrain patients in their independence of activities of daily living. Exercise therapy is used in the multi disciplinary treatment of rheumatoid arthritis to maintain and improve endurance, muscle strength and range of motion. Consistent effects could not be recorded so far. Objectives: The main objective of this study is to determine the effects of regular exercise therapy in treating RA. The secondary objectives are to differentiate the effects of high or low intensity exercise therapy, and exercise therapy in patients with early or longstanding RA. Search methods: Databases Medline, Pedro, Cochrane Central Register of Controlled Trials, Springer and Thieme were searched for RCTs published between 1998 and 2009 using the terms rheumatoid arthritis and exercise therapy OR exercise, functional training, dynamic exercise, “motion therapy,” movement therapy. The search was carried out between November 2008 and May 2009. Data collection and analysis: Study and participant characteristics plus relevant outcome measures were extracted. Primary outcome measures were functional skill and pain. Secondary outcome measures were muscle strength, endurance, joint motion, joint erosion, bone density and activity of disease. Methodological quality was assessed using the PEDro Rating Scale. For each outcome measure the effect size of every study was calculated. Results: 14 out of 41 selected articles met the inclusion criteria, ten of them presenting data from two studies. Positive effects on muscle strength (d 0.07-0.89) and functional capacity (d 0.1-1.89) were found. Due to the small number of studies included, only tendencies for positive effects on joint damage, bone density of the lumbar spine and endurance could be reported. Inconclusive data was found for disease activity and bone density of the femur. Discussion: Considering the results two weaknesses stand out: The predominantly very low outcome results and the heterogeneity of the impact of the results per outcome. The heterogeneity included differences between positive or negative efficacy in principle. The small number of studies affects the internal validity. For better evidence in future a systematic review should include more studies with the outcomes of endurance, joint motion, joint erosion and bone density, because these areas incur essential alterations in progress of the disease. Conclusion: Regular exercise therapy does show small to medium positive effects for functional capacity and muscle strength in patients with RA. The evidence of results is limited due to the small number of studies included and heterogeneity of effect sizes.