Sodium dodecyl sulphate-polyacrylamide gel electrophoresis is a method allowing the separation of proteins according to their molecular sizes. For this reason this method is rather useful for the classification of proteinurias as tubular, glomerular, or mixed. In the present study a good correlation was observed between the results of urine electrophoresis in sodium dodecyl sulphate-polyacrylamide gel and both clinical and histopathological data from 32 patients with different forms of renal disease.