An attempt has been made to compare the activity and specificity of pregastric esterase and pancreatic lipase from calves 1-2 weeks of age in an in vitro system using washed milk-fat globules as substrate. In addition, the changes in activity of pancreatic lipase and pancreatic phospholipase have been investigated as milk-fed calves change from a monogastric to a ruminant type of digestion.