Abstract With the widely used disc electrophoresis technique of Ornstein and Davis, considerable part of the immunoglobulins is retained within the turbid concentration gel. A modification of this technique is described which allows better evaluation of these retained immunoglobulins. Using a modified concentration gel the bulk of IgG and all IgM are separated from IgA. Since concentration and separation gels have identical transparencies, densitometry can easily be performed. The normal protein pattern of human serum is described and the separation principles in both gel types are discussed.