Lactase-deficient adults demonstrate improved lactose absorption and fewer symptoms when consuming yogurt than when consuming milk containing equivalent amounts of lactose. To examine this effect and its mechanisms in children, we compared symptoms and hydrogen production as an index of lactose malabsorption after typical servings of milk, pasteurized yogurt, and yogurt containing active live culture in 14 lactose-malabsorbing children (mean age 9.5 y). Symptoms and interval breath-hydrogen concentrations were recorded for 8 h after ingestion of 12 g lactose served as milk and yogurts. Lactose-malabsorbing children experienced significantly fewer symptoms after consuming yogurt containing active cultures than after consuming milk (P < 0.005). Pasteurized yogurt showed an intermediate effect. Lactose from yogurt was not better absorbed than was lactose from milk, as indicated by similar areas under the hydrogen curve; however, yogurt was associated with a delayed time to rise and lower rate of rise of the hydrogen curve. The rate of hydrogen rise correlated with the degree of symptoms. In children, mechanisms other than enhanced lactose absorption from yogurt may lead to changes in the kinetics of hydrogen production, which in turn are associated with improved tolerance.