Objective To perspectively evaluate the long-term efficacy of low dose leflunomide in treatment of rheumatoid arthritis.Methods Twenty-eight patients with rheumatoid arthritis were randomly divided into treatment group( n =15 ) and control group ( n =13 ).The patients in treatment group were treated with low dose leflunomide( omitting the loading dose) and with maintenance dose of 10 mg/day.And the patients in control group were treated with sulphasalazine in the dose of 1.5 ～ 2.0 g/d.The observation lasted for 18 months and the observed indicator were as follows:( 1 ) The primary efficacy indicators:counts of swollen and tender joints,overall assessment of disease status made by patients and physicians; ( 2 ) Secondary efficacy indicators:pain visual analogue scale,duration of morning stiffness,health assessment questionnaire (HAQ),Creaction protein,the American College of Rheumatology Outcome Assessment (ACR20,50).Results Eighteen months after treatment,the primary efficacy indicators in the treatment group were superior to the control group ( swollen joint counts:( - 8.5 ± 6.3 ) vs ( - 7.9 ± 6.4) ; overall assessment by patients:( - 1.4 ± 0.8 ) points vs ( - 1.2 ± 0.6) points; overall assessment by physicians:( - 1.4 ± 1.2 ) points vs ( - 1.3 ± 0.9 ) points; P ＜0.01 ).In the secondary efficacy indicators,pain visual analogue scale,duration of morning stiffness and health assessment questionnaire(HAQ) in the treatment group were significantly improved compared with the control group(VAS score:( - 32.4 ± 23.7) points vs ( - 31.6 ± 24.8) points; duration of morning stiffness:( [ - 97.8 ± 6.2 ] min vs [ - 92.4 ± 5.2 ] min; HAQ:[ - 0.62 ± 0.08 ] points vs [ - 0.57 ± 0.02 ] points,P ＜0.01 ),there was no significant difference on the percentage of patients achieving ACR20 standard between the treatment group and the control group (76.9％ vs 75.0％,P ＞ 0.05 ),but there was significant difference on the percentage of patients achieving ACRS0 standard between the treatment group and the control group( 61.5％ vs 47.0％,P ＜ 0.05 ).The gastrointestinaladverse reactions for patients in the treatment group were mild and there were 2 cases of elevated blood pressure,2 cases of elevated liver enzymes and 2 cases out of the trail,in the control group,there was 1 case out of the trial.Conclusion The long-term treatment of active rheumatoid arthritis with low dose leflunomide can achieve exact efficacy and good tolerability compared with the treatment with sulfasalasine.