Data Synthesis: The need for objective, evidence-based guidance on the role of probiotics is becoming increasingly important as public awareness grows. This consensus is intended as a practical reference to help physicians make appropriate, evidence-based recommendations to patients who might benefit from probiotic treatment. Overall, the randomised, placebo-controlled trials included in this article support, with a high evidence level, the therapeutic effects of probiotic agents for several disorders including antibiotic or Clostridium difficile-associated diarrhea, irritable bowel syndrome, and the inflammatory bowel diseases. Although probiotic research is a rapidly evolving field, there are sufficient data to justify a trial of probiotics for treatment or prevention of some of these conditions. However, the capacity of probiotics to modify disease symptoms is likely to be modest and varies among probiotic strains and not all probiotics are right for all diseases. The goal of this review is to provide clinicians with an overview of the rationale and data which support or refute the role of probiotics for treating commonly encountered gastrointestinal disorders.