The aim of this study was to evaluate the role of magnetic resonance imaging (MRI) of the wrist joint of RA patient in the early diagnosis of the disease. 60 patients were selected [25 patients who have late RA, 25 patients who suspected to have early RA, and 10 patients with other inflammatory joint disease (as control)]. The most common joint showed to have periarticular enhancement (synovitis) on MR images were the intercarpal joints in late RA patients, and the ulnocarpal joints in early RA patients. The periarticular enhancement (synovitis) on MR images of both wrists was significantly associated with number of swollen joints, number of tender joints, Ritchie articular index, functional class, wrist swelling, tenderness and grip strength. When using the MR imaging criterion of active synovitis in the ACR 1987 classification tree format, the sensitivity and specificity were improved to 100% and 90% respectively. The accuracy was 97% and the negative predictive values were 100%. Conclusion: The diagnosis of early RA is improved when the MR imaging criterion of active synovitis is incorporated into the classification tree format of the 1987 ACR revised criteria for diagnosis of RA.