Abstract Single shelled lecithin vesicles of uniform size ( diameter = 300 A ̊ ) are prepared without sonication by solubilizing unsonicated lecithin dispersions with sodium cholate and removing the detergent from the mixed lecithin — cholate micelles by gel filtration on Sephadex G-50. A homogeneous population of pure lecithin single — bilayer vesicles free of multilamellar structures is obtained. The vesicle diameter is somewhat larger than the average diameter of sonicated vesicles. The curvature of the bilayer seems to be sufficiently large to allow for similar packing densities (areas/molecule) on the outer and inner layer of the bilayer. The morphology and some physico-chemical properties of these vesicles are described and compared with those of sonicated vesicles.