Background : Interferons are naturally occuring cytokines with many biologic properties. Interferon-gamma has immunomodulatory as well as antiviral and antiproliferative actions. Recently many uncontrolled and controlled studies have shown some clinical improvement in rheumatoid arthritis(RA) with interferon-gamma therapy. The work reported here was designed to compare the therapeutic potential of interferon-gamma and placebo in the patients with RA. Methods : Thirty-six patients entered this study and 31 completed the 4-week period. The patients received a subcutaneous injection of $IFN-{gamma}(1{ imes}10^6IU)$ or placebo daily for 20 days. and then every other day up to day 28. Results : Among the 31 evaluable patients. 16 patients received $IFN-{gamma}$ and 15 patients, placebo. According to predetermined response criteria. responders were found more frequently in the group treated with $IFN-{gamma}(50%)$ than in the placebo group(15.4%) (p=0.035) Patients who were treated with $IFN-{gamma}$ improved significantly with respect to Ritchie index, tender joint count ADL pain, and movement pain. Hepatitis developed in one patient of $IFN-{gamma}$ group, and the liver enzyme levels normalized with discontinuation of the drug. Adverse events were more common in $IFN-{gamma}$ group but not so serious. Conclusion : We conclude that $IFN-{gamma}$ is effective as a therapeutic drug of RA and has no significant adverse events.