(1) Sugars utilized by the yeastSaccharomyces cerevisia (glucosamine) can be found in a free state in the cells if the rate of their utilization is lower than the rate of uptake. (2) Glucosamine accumulates in the cells in a chemically bound form, on the one hand (occasionally at a concentration greater than that of extracellular free glucosamine), and in a chemically unaltered form, on the other. The uptake of free glucosamine proceeds according to its concentration gradient. (3) The relationship between the uptake of glucosamine and the pH of the medium indicates that glucosamine will cross the cell membrane only in the undissociated form. (4) The dependence of the initial rate of uptake of glucosamine on its external concentration obeys saturation kinetics. (5) Both utilized and non-utilized (non-phosphorylated) sugars inhibit the uptake of glucosamine by the yeast, both with and without 10−3M-iodoacetate in the medium. (6) The above results suggest that there is no difference between the mechanism of uptake of utilized and non-utilized sugars.