A method was developed for high resolution electrophoresis of proteins in linear gradient (3 to 30%) polyacrylamide gel rods in a neutral phosphate buffer containing 0.1% sodium dodecyl sulfate. Well-defined protein zones were observed and improved resolution was attained especially for low molecular weight proteins in preparations containing a variety of polypeptides, e.g. viruses that are often separated by continuous gel methods. Electropherograms of continuous (8%) and gradient (3 to 30%) gels were made of purified vesicular stomatitis virus, variola virus, Rickettsia rickettsii, and alpha and beta chains of hemoglobin in order to demonstrate the resolution of the gradient system.