OBJECTIVE To evaluate the extended follow-up data on efficacy and toxicity of leflunomide therapy in Takayasu arteritis (TA) patients previously enrolled in the original open-label study of short-term effects of leflunomide in TA. METHODS An open-label long-term longitudinal study was performed in TA patients who fulfilled the 1990 American College of Rheumatology criteria for TA and had participated in a previous study that evaluated short-term efficacy of leflunomide in TA. Complete follow-up information could be retrieved from 12 out of 15 patients enrolled in the original study. Disease activity was evaluated by Kerr's criteria and by the Indian Takayasu Activity Score 2010 (ITAS2010). RESULTS The mean follow up time was 43.0±7.6 months and 5 (41.6%) TA patients remained on leflunomide therapy while 7 (58.3%) TA patients had to change to another therapy due to failure to prevent relapses in 6 patients and toxicity in one patient. No significant differences were found between patients who remained on leflunomide therapy and those who changed to another agent regarding age at study entry, time since diagnosis, prednisone daily dose at study entry, baseline ITAS2010, mean or maximum ESR and CRP, and cumulative prednisone dose at study end. Among two TA patients who had changed laflunomide to another agent, two had a clinical relapse and needed to change therapy. CONCLUSIONS Leflunomide led to sustained remission in approximately half of patients at a mean time of 12 months and was well tolerated by TA patients.