Backgrounds/Aims: It has been clarified the difference of genetic background of Crohn’s disease (CD) between the patients in US and Japanese patients, such as the incidence of NOD2 mutation. Moreover, diversities of therapeutic regimens that have been applied to Japanese patients with CD are present, such as a long-term application of elemental diet, or less frequent use of 6MP/AZA. In this study, we purposed to verify the efficacy of Infliximab administration on Japanese CD patients by assessing the sequential changes of symptomatic and luminal disease activities. Patients/Methods: Forty-eight CD patients were administrated with 5 mg/kg of Infliximab by one or three-dose regimen in Asahikawa Medical College Hospital , from June/2002 to Decune/2004. CDAI was calculated at every two weeks before and after the administration for a year. Serum CRP levels were also measured as a marker of inflammation. Luminal activities were determined by colonoscopic examination before and at 4 week after the first administration. Thirty-four out of 48 patients received maintenance doses of 5 mg/kg Infliximab at every 8 weeks. Re-admission rate after remission-induction by Infliximab was calculated as a marker of long-term efficacy. Results: Initial CDAI of the patients was 230.4±76.0. Response rate (25% or 75 points reduction of pretreatment CDAI) at 2 week after the first infusion was 56.3%, whereas total remission rate (CDAI below 150) until 8 week was 84.3%. Luminal disease activity was improved at 4 week after the first injection in 82.3% of patients tested, and especially the decrease of density of aphthous ulcers in left side colon was noted in 85.7% of patients. Re-admission within 2 years after initial injection occurred 41.7% of the patients. Logistic regression analysis performed to elucidate the risk factor of earlier re-admission revealed that the postsurgical residual intestine less than 200 mm was a significant risk factor, whereas the scheduled administration of Infliximab detected as a preventing factor. (Table). Conclusions: Despite the difference of genetic background and therapeutic environment, Japanese CD patients in our institute showed remarkable response to Infliximab in both symptomatic and luminal disease activities. Postsurgical patients with short residual intestine should have the significant risk of earlier relapse through Infliximab treatment.