SUMMARY The effect of a new complex oligosaccharide exhibiting potent inhibitory action on ax-glucoside hydrolases on intestinal absorption of sucrose in man was tested by constant in vivo perfusion of the jejunum. At concentrations of 4-65 or 155 x 10-6M the ac-glucosidehydrolase inhibitor (a-GHI) markedly inhibited absorption of glucose from sucrose and absorption of sodium and water. Oral administration of the a-GHI resulted as well in depression of solute, sodium, and water absorption. This new compound can serve as an interesting tool to induce carbohydrate malabsorption by inhibition of final digestion and may possibly be of beneficial therapeutic effect in dietary control of diabetes or obesity.