An extract of human intestinal mucosa can degrade glycogen, isomaltose, sucrose and maltose through the action of several hydrolytic enzymes, which have been identified by experiments of competition between substrates and by some other properties. Besides an α‐amylase, which is soluble and probably of pancreatic origin, three truly intestinal α‐glucosidases are bound to cellular structures: a glucoamylase forms glucose from glycogen (Km= 0.65 mg/ml) and maltose (Km= 2 mM), a maltase‐isomaltase, from maltose (Km= 1 mM) and isomaltose (Km= 7 mM) and a maltase‐sucrase, from maltose (Km= 7 mM) and sucrose (Km= 17 mM). Copyright © 1969, Wiley Blackwell. All rights reserved