At birth both pancreatic lipase and carboxylic ester hydrolase, two important lipolytic enzymes secreted by the pancreas, are present in duodenal contents but the activities of these enzymes are low. Another enzyme of possible importance in lipolysis is the lingual lipase which is secreted from serous glands present at the posterior part of the tongue. The enzyme is present already at birth and has been found in gastric contents from preterm infants in the 34th gestational week. The secretion of lingual lipase is stimulated by feeding and it is resistent against acid inactivation. The activity in gastric contents increases after feeding. This lipase hydrolyzes dietary triglycerides to mainly diglycerides and free fatty acids and may serve as a complement to the poorly developed pancreatic lipase activity. Furthermore, by the formation of polar lipolytic products the digestibility of dietary lipids in the duodenum may increase. Human milk lipase contributes to the lipolysis. It is inactive in the milk but becomes activated by the bile acids in the duodenum. Balance studies in preterm infants have shown that by pasteurization of human milk fat absorption decreases by one third.