It was recently reported that exercise is related to immunity and inflammation system although some controversy remains. The purpose of this study was to investigate the anti-inflammatory effect according to swimming exercise intensity in rheumatoid arthritis. Experimental groups were divided into 4 groups: group I (n=8, control group), group II (n=8, non weight-bearing swimming exercise), group III (n=8, 5% weight-bearing swimming exercise) and group IV (n=8, 10% weight bearing swimming exercise). The swimming exercises were designed for swimming 3 days per week for total of 3 weeks. Anti-inflammatory effect was measured by paw volume, arthritis index, gross & histology examination. As a result, Swimming exercise groups II, III, IV were significantly more effective than group I. Especially, group III showed the most effective response of all swimming groups. Therefore, we suggested that swimming exercise improves antiinflammatory effects in rheumatoid arthritis. Especially, moderate swimming exercise was the most effective in the antiinflammatory.