Abstract: Improved resolution of proteins and other macro molecules in gel electrophoresis is obtained by causing the molecules to move through the gel under the influence of an electrical potential, the polarity of which is intermittently reversed. While the current is reversed for a brief period, any molecules that have become trapped in pores in the gel have an opportunity to escape. For proteins, the frequency of current reversal should be from 1 to 5,000 reversals per second and the influence of the reverse current should not be greater than 50% of the forward or driving current. Current reversal can be used in combination with multiple transverse electrical fields.