Probiotics are live nonpathogenic bacteria or bacterial components that may be helpful in the prevention and treatment of acute diarrhoea in adults and children and have some effects on the course of inflammatory bowel diseases (IBD). Many experimental and clinical studies suggest that intestinal bacterial flora plays an important role in the pathogenesis of IBD, and manipulation of the luminal contents with antibiotics or probiotics represents a potentially effective therapeutic option. The beneficial effect of probiotics was demonstrated mainly in the prevention and treatment of pouchitis and in maintaining remission of mild to moderate ulcerative colitis. Probiotics seems to be less effective in patients with Crohn's disease. Randomized clinical trials are still required to further define the role of probiotics as preventive and therapeutic agents. This review summarizes the current data about probiotics in IBD.