Effect of administration of Lactobacillus rhamnosus GG on the postprandial blood glucose elevation was investigated by sugar tolerance tests in rats. Wistar male rats (8-weeks-old) were fed diets supplemented with lyophilized cells of L. rhamnosus GG for 14 days. After oral administration of maltose or glucose, the elevation of blood glucose level was significantly suppressed by the intake of L. rhamnosus GG. In in vitro study, L. rhamnosus GG showed glucose-decreasing action and the action of viable cells was higher than that of heat-sterilized cells. These results suggested that L. rhamnosus GG suppressed the postprandial hyperglycemia by inhibiting glucose absorption, and the inhibition might be due to binding and assimilation of the glucose.