Abstract: A method of stacking or condensing DNA or other samples prior to electrophoresis to improve electrophoretic resolution. A sample material is placed on a separation medium, e.g., polyacrylamide or agarose gel. A relatively low voltage is applied across the sample for a short period to stack or condense the sample material without significantly transporting the sample material into the separation medium. A large voltage is then applied to inject the stacked sample material into the separation medium.