Investigation of the hydrolysis of phosphatidylcholines (lecithins) in hot aqueous alcohol under the influence of mercuric chloride has shown that glycerylphosphorylcholine is formed and that neither racemization nor migration of the phosphorylcholine moiety occurs. The fatty acids are split off much more rapidly than is choline and as a consequence appreciable amounts of glycerylphosphorylcholine are formed. On the basis of these observations a procedure was devised for the hydrolysis of crude lecithin and the isolation of glycerylphosphorylcholine in a yield of 69%. The product was identified as L-α-glycerylphosphorylcholine by analysis of its cadmium chloride complex, and comparison of its optical rotation with that of the synthetic compound of known configuration. Recovery of the diester from this complex was accomplished through removal of the inorganic salt by ion-exchange resins and the free L-α-glycerylphosphorylcholine was crystallized from 99% ethanol.