During the past several years there have been many reports of alternative dietary therapies for primary and secondary lactose intolerance. We have learned that it is useful to feed through most episodes of mild diarrhea that previously would have been treated with clear liquid diets. Infant formulas, including both soy-protein and hydrolysate formulas with specially designed carbohydrate, protein, and fat components, are available to treat the infant with diarrheal syndromes and secondary lactase deficiency. Also, the diet can be supplemented with lactase. Specialized lactose-reduced products as well as cultured and fermented dairy products may be used in varying degrees for lactose-intolerant children. The ingestion of milk with food and fiber components in the diet has also been shown to improve symptoms of lactose intolerance. This review summarizes the essentials of diagnosis of and dietary therapy for lactose intolerance. Our findings indicate that a number of specialized formulas and products are available for successful dietary management of lactose intolerance in infants and children.