To date few therapies have been shown to reliably prevent the evolution of Crohn's disease (CD). The traditional Chinese medicine, Tripterygium wilfordii Hook F (TWHF), has both immunomodulatory and anti-inflammatory activities. Our aim was to investigate the potential efficacy of T2, the major constituent of extracts of TWHF, in inducing remission of active CD. Twenty adult patients with active CD were enrolled to be treated with T2 pills (60 mg daily) for 12 weeks. Plasma levels of C-reactive protein (CRP), tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1beta were measured at entry and every 2 weeks thereafter until week 12. At each visit the CD Activity Index (CDAI) was calculated. The CD Endoscopic Index of Severity was measured at entry and week 12. Sixteen patients completed the study. A significant decrease in serum levels of CRP, TNF-alpha, and IL-1beta occurred rapidly after commencement of treatment. CDAI scores showed a rapid decline during the first 8 weeks and reached their lowest at week 10. Endoscopic improvements were observed at week 12. In conclusion, T2 appears to be effective for the treatment of mildly or moderately active CD. Further controlled studies are warranted for this promising drug.