[en] Background: Seventy percent of Crohn's disease (CD) patients exhibit anastomotic recurrence within I year after ileo-caecal surgery, Recent clinical trials suggest the beneficial use of probiotics in the control of intestinal inflammation in pouchitis and ulcerative colitis. This study is a multicenter clinical trial evaluating the efficacy of an oral administration of the probiotic LA1 on early postoperative endoscopic recurrence of CD. Methods: Seventy patients with CD were enrolled prior to elective ileo-caecal resection and randomly assigned after surgery to daily treatment with either Lactobacillus johnsonii, LA1, Nestle (10(10) colony-forming units, CFU) (group A, n = 34) or placebo (group B, n = 36) for 12 weeks. The primary objective was to assess the effect of LA1 on the endoscopic recurrence rate at 12 weeks. Stratification was performed according to smoking status at randomization. Results: Seven and 14 patients were excluded in the LA1 and placebo groups, respectively. In intention-to-treat analysis, the mean endoscopic score was not significantly different between the two treatment groups at 3 months (LA1 versus placebo: 1.50 +/- 1.32 versus 1.22 +/- 1.37, treatment effect: P = 0.48, smoke effect: P = 0.72). The percentage of patients with severe recurrence (i3 + i4) was 21% and 15% in the LA1 and placebo groups, respectively (P = 0.33). Using a per-protocol (PP) analysis, the mean endoscopic score was not significantly different between the two treatment groups (LA1 versus placebo groups: 1.44 +/- 1.31 versus 1.05 +/- 1.21, P = 0.32). The percentage of patients with severe recurrence (i3 + i4) was 19% and 9% in the LA1 and placebo groups, respectively (P = 0.054). Clinical relapse rate (CDAI [CD activity index] > 150, with an increase of CDAI > 70 points or greater from baseline) in the LAI and placebo groups was 15% (4/27) and 13.5% (3/22), respectively (PP analysis: chi-square test, P = 0.91 and log-rank test: P = 0.79). Conclusion: Oral administration of the probiotic LA1 in patients with CID failed to prevent early endoscopic recurrence at 12 weeks after ileo-caecal resection.