Abstract: Reactive Oxygen Species (ROS) play an important role in the pathogenesis of Rheumatoid Arthritis (RA) exposing these patients to oxidative stress. The aim of the present study was to evaluate the effects of antioxidant supplementations on oxidative status and disease activity in RA patients. Forty nine RA patients (41 females, 8 males, age 48.78±12.54 years) participated in this randomized clinical trial. Patients were randomly divided into two groups to received antioxidant supplementations in combined with conventional treatment (Group I, n: 24) or conventional treatment only (group II, n: 25) for 12 weeks. Plasma concentration of malondialdehyde (MDA) and Total Antioxidant Capacity (TAC) were measured at the beginning of the study and after intervention in both groups. Disease activity was also measured before and after intervention using Rheumatoid Arthritis Disease Activity Index (RADAI). Supplementation with antioxidant yielded significantly decreased in plasma MDA concentration (p<0.0001) and disease activity (p<0.0001) and statistically increased in TAC levels (p<0.0001) in group I in comparison to group II after 12 weeks. This study indicates that antioxidant supplementations may play an important role in improving oxidative stress and decreasing disease activity in these patients.