Summary An immunoelectrophoretic method based upon one-dimensional and two-dimensional zone electrophoresis is described in detail. A discontinuous system of buffers was used in order to increase the resolving power of the starch-gel electrophoresis and to increase the sensitivity of the antigen-antibody reactions in agar gel. Results obtained with two-dimensional zone immunoelectrophoresis include a) demonstration of several “albumin like” proteins in a nephrotic serum and b) localization of an acidic α-1-glycoprotein (orosomucoid) in urine. Results obtained with the one-dimensional technique demonstrate a) immunologic specificity of crystalline transferrin (β-1-globulin) after interaction with diphtheria toxin and b) heterogeneity of crystalline diphtheria toxin and highly purified tetanus toxoid. Differences between the method of Grabar and Williams and the methods described are fully discussed.