We describe a modified polyacrylamide gel electrophoresis method with which plasma proteins are excellently resolved in 4 h. We made a three-layer discontinuous gradient gel with concentrations of 80,60, and 45 g of polyacrylamide per liter of tris(hydroxymethyl)aminomethane/ethylenediaminetetraacetic acid/borate buffer, pH 9.2. Time and material needed in the preparation of the gel was greatly decreased, a well-resolved (22-25 bands) pattern was obtained in 1 h, and the gel slabs were easier to remove from the cell than were gels prepared according to the manufacturer's specifications. We saw a marked shift in the higher polymers of haptoglobin type 2-2 toward the cathode in this system, and also a clearly resolved double band of alpha2-macroglobulin in whichthe more anodal band appears to represent alpha2-macroglobulin/protease complex.