In the presence of 0.1 M glycine, pH 2.5, a-crystallin dissociates into aggregates containing onlyαA chains plus monomericαB chains. Advantage has been taken of this to develop a method for the purification of theαA andαB chains by gel filtration on Sephadex G-75. This method gives high yields of purified subunits and avoids the risk of carbamylation associated with other methods which use high concentrations ofurea.