Interest in nutritional supplements and functional foods has risen significantly in recent years. Many of the products that are marketed to consumers tout the benefits of probiotics for general good health and for a wide variety of conditions and situations. Although most of these products have been used safely for years, careful analysis of scientific research should be conducted before routinely recommending these products, especially for children. A basic understanding of intestinal flora, properties of probiotics, and clinical research findings is necessary for clinicians to delineate the role of probiotic agents in the pediatric population.