treating rheumatoid arthritis.　METHODS: Eighty patients with rheumatoid arthritis were randomly divided into two groups with each group having 40 patients. Group one (M 8, F 32; age 46 a± s 11 a; disease history 63 mo±48 mo) was treated with anti-inflammation sub-group No.1 and No.3. Group two (M 6, F 34; 44 a±9 a; disease history 45 mo±45 mo) was treated with sub-group No.2 and No.4. One week before the initiate of the study, the originally used non-steroid anti-inflammation drugs were stopped for all two-groups patients and each patient took 2 tablets of oxaprozin po qn. At the beginning of the study the patients received 2 tablets of anti-inflammation drugs No.1 daily and 6 tables of No.3 weekly in 1st group, and 2 tablets of anti-inflammation drugs No.2 daily and 6 tablets of No.4 weekly in 2nd group respectively.　RESULTS: In the leflunomide group, the total effect rate was 93 % and the remarkable improvement rate was 85 %. In the methotrexate group, the total effect rate was also 93 % and the remarkable effect rate was 83 %, P>0.05. Nine patients (23 %) in leflunomide group had adverse reaction as mainly skin itch, nettle-like rash, decrease of leukocytes, liver malfunction and others. Seventeen parients (43 %) in methotrexate group had adverse reaction as mainly responses of digestive tract, liver enzyme elevation, decrease of leukocytes, trichomadesis, manoxenia, and others.　CONCLUSION: Leflunomide has similar therapeutic efficacy to methotrexate. However, it has relatively less toxicity.