Blood glucose concentrations were measured two times in the same 7 patients who had undergone total gastrectomy 0, 20, 50, 80 and 120 min after two glucose meals (50 g of glucose and 100 ml of water), which on a double-blind basis contained 5 g of guar gum and 5 g of wheat flour in random order. The mean blood glucose concentration was significantly (p < 0.01–0.001) lower 20, 80 and 120 min after the meal containing guar gum than after the meal containing wheat flour. All patients except two (one 50 min and the other 80 and 120 min postprandially) had lower blood glucose concentrations after the meals containing guar gum than after the meals containing wheat flour. Three of four patients who used 5 g guar gum three times daily in their meals felt it benefical in preventing dumping-like symptoms. One got disturbing meteorism. It was concluded that guar gum decreased glucose absorption and prevented postprandial hyperglycemia in these total gastrectomy patients. Guar gum may facilitate the planning of diets for such patient