BACKGROUND AND AIMS: Previous studies have indicated that thalidomide may be effective in achieving clinical remission and response; however, there is a lack of studies on its effect in endoscopic remission. The aim of this study was to assess the efficacy and safety of thalidomide in inducing and maintaining endoscopic remission. METHODS: A retrospective study was conducted in adult Crohn's disease (CD) patients treated with thalidomide. Patients were assessed based on their medical records. Endoscopy was performed after 4-6 months of thalidomide administration, and the simple endoscopic score for CD (SES-CD) was obtained. RESULTS: Twenty of the 21 (95.2%) eligible patients were recruited. Endoscopic remission was achieved in 7 of the 14 (50%) endoscopy active patients who received thalidomide treatment, whereas 10 (71.4%) patients showed an endoscopy response. The other 6 patients in endoscopic remission still maintained remission after thalidomide treatment. The SES-CD in endoscopy active patients was significantly reduced after thalidomide treatment (P<0.05). A total of 32 adverse events occurred in 17 of the 21 (81.0%) patients. Adverse events resolved spontaneously in 11 (64.7%) patients and resulted in treatment discontinuation and dose reduction in 4 (19.1%) and 2 (9.5%) patients, respectively. CONCLUSIONS: Thalidomide therapy is effective in inducing and maintaining endoscopic remission in adult CD patients. However, side effects may limit its clinical use in CD treatment.