Thalidomide is an oral agent that has immunomodulatory, antiangiogenic and TNF(tumor necrosis factor)-a- suppressing effects. The potential role for thalidomide in the treatment of refractory paediatric and adult CD has been investigated in more and more small open-label studies and retrospective case series. Recently, a randomized controlled trial showed thalidomide improved clinical remission at 8 weeks of treatment and longer-term maintenance of remission in pediatric refractory CD. Gerich et al reported in a retrospective study that thalidomide improved long-term outcomes among 37 refractory CD adults followed up for a median of 58 months. However, the dose of thalidomide used in these studies ranged from 50mg/d to 150mg/d, and the occurrence rate of side effects reported variously but all quite high. The side effects related to the dose of thalidomide were the major concerns of using it in CD. Moreover, the effect of thalidomide on endoscopic response including mucosal healing which is a more objective and important outcome in CD was rarely reported. Therefore the aim of this study is to investigate the efficacy on clinical and endoscopic response and the adverse effects of using low-dose thalidomide in active adult CD patients.