A simple method of horizontal polyacrylamide gel electrophoresis was described for the simultaneous phenotyping of transferrin, post-transfemn, albumin and postalbumin in the blood plasma of cattle. A step gradient gel of 8, 4, 12 and 14 % acrylamide concentration was used. The method enabled the detection of a new protein polymorphism in ,the post-transfenin region. Two alleles were observed.The transferrin phenotypes involving D, and D, alleles were clearly separated. The resolution of the post-albumin fractions was also better than described by earlier methods.