A simple method of horizontal polyacrylamide gel electrophoresis was described for the simultaneous phenotyping of transferrin, post-transferrin, albumin and post-albumin 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-transferrin region. Two alleles were observed. The transferrin phenotypes involving D1 and D2 alleles were clearly separated. The resolution of the post-albumin fractions was also better than described by earlier methods.