The efficacy of leflunomide in the treatment of early rheumatoid arthritis (RA) patients might be attributed to the fact that it acts at several levels, including the anti-inflammatory and anti-destructive pathways. This is in addition to its inhibition of the L-dihydro-orotate dehydrogenase (DHOH) enzyme and pyrimidine de novo synthesis which decreases cell proliferation and more specifically early activated CD4+ T cells, as well as monocyte interaction with T cells leading to cytokine and anticytokine production. Recent studies clearly indicate the rationale of an early administration of leflunomide in RA patients, particularly in the light of the results of previously reported clinical studies showing its rapid onset of action when compared to other DMARDs. The early efficacy and safety of leflunomide in patients with early RA is sustained over a long period, and the long-term safety profile of leflunomide does not seem to be different from that observed in phase III trials.