Carbohydrate malabsorption is a very important clinical entity, particularly in pediatrics, where, if untreated, it can lead to malnutrition and failure to thrive. Malabsorption that can be treated readily with elimination of the offending carbohydrate. Knowledge by the physician of the specific mechanisms involved in the physiology of carbohydrate absorption and digestion will help in the handling of the clinical situation of malabsorption.