Probiotics are dietary foods or supplements that include viable microorganisms which affect the microflora of the host. Their use is beneficial in preventing antibiotic-associated diarrhea and treating acute viral gastroenteritis in healthy children. Prebiotics are dietary foods or supplements which include a food element that cannot be digested but instead promotes the activity and growth of native probiotic bacteria. Human milk comprises a high concentration of prebiotics and contains a significant amount of oligosaccharides, which are prebiotic components. These oligosaccharides are responsible for preventing pathogenic infection, developing the immune system, and regulation of the bifidogenic and gastrointestinal microbiota in infants. Prebiotics and probiotics have a significant impact on the composition of the gastrointestinal flora. Probiotics have been used to prevent and treat a wide range of diseases in both adults and children. This book provides significant information to help develop a good understanding on the role of prebiotics and probiotics in pediatric medicine. Those in search of information to further their knowledge will be greatly assisted by it.