Membrane-bound bodies are formed individually and in groups from the plasma membrane surrounding the microvilli in cells of hamster small intestine. These bodies are vesiculate structures, are slightly smaller in diameter than the microvilli from which they are released, and retain at least a portion of glycocalyx. The production of the membrane-bodies occurs regularly, perhaps continuously in vivo, and appears to be related to the feeding cycle. The brush border of jejunal cells from animals which had been feeding ad lib contained more membrane-bodies andhad taller microvilli than comparable cells from those which had been fasted for 48 hours. Since membrane-bodies are also found among the microvilli of cells which have no digestive function, we propose that their formation and release may be of general significance in the normal functioning of active epithelial cells.