Abstract Homogenates of rat intestinal mucosa phosphorylate glucose, fructose, mannose, glucosamine, 2-deoxyglucose, allose and l -sorbose. No phosphorylation of galactose or 3-methylglucose has been observed. With the exception of l -sorbose, the phosphorylations are carried out by a single enzyme with a pattern of specifictty similar to that of brain hexokinase. The hexoses appear to be phosphorylated in the 6 position. Glucose-6-phosphate inhibits the enzyme. The data indicate that hexokinase is not a part of the mechanism of intestinal absorption of sugars.