Probiotics have been studied in a variety of GI infections, and are an appealing concept given their favorable safety profiles. Several placebo-controlled trials indicated that lactobacilli have a suppressive effect on H pylori infection. Although some studies reported improvement in H pylori eradication, others failed to confirm this. Controlled trials support the use of Lactobacillus GG and S boulardii for the prevention of AAD, and have demonstrated the effectiveness of S boulardii as adjunctive therapy for RCDAD. Several placebo-controlled trials showed a reduction in the severity and duration of acute diarrhea in children with use of Lactobacillus GG. Studies of probiotics for the prevention of traveler's diarrhea yielded conflicting results, and their routine use cannot be recommended in this setting. Preliminary evidence suggests a potential role for reducing secondary pancreatic infections, although conclusive evidence is not available at this time. Additional clinical trials are indicated to define the role of probiotics further before wide-spread use can be recommended.