A method is described for electrophoresing lipoproteins in polyacrylamide gels, in which separations depend both on electrophoretic mobility and molecular size. The sample is prestained with Sudan Black B in a sample gel and then resolved by electrophoresis in a discontinuous pH system consisting of a sample gel, concentrating gel, and separating gel. This method was compared with the paper electrophoretic method of Lees and Hatch [J. Lab. Clin. Med. 61, 518(1963)] and was found to be equally useful in phenotyping lipoproteinemias, with two distinct improvements over paper electrophoretic methods: lipoproteins are more quickly and discretely separated.