Many experimental and clinical observations suggest a potential role for intestinal microflora in the pathogenesis of inflammatory bowel disease. Manipulation of the luminal content using antibiotics and/or probiotics may represent a potentially effective therapeutic option. Results of antibiotic treatment in inflammatory bowel disease are controversial, but this approach is frequently and successfully adopted in clinical practice. Recent data support the potential therapeutic role of probiotics in inflammatory bowel disease. In particular, a highly concentrated probiotic preparation was shown to be superior to placebo both on the prevention of pouchitis onset and of chronic pouchitis relapse. Its role in the maintenance treatment of ulcerative colitis and Crohn disease needs to be further assessed by large, double-blind, controlled trials. Future research needs to be focused on obtaining more precise information on the enteric microflora and the mechanisms of action of probiotics.