The possibility of protein separation in an organic solvent medium was tested at 6 or 7 kV. The sample protein solution was a microaqueous system prepared by mixing an aqueous protein solution with organic solvents. Casein, alpha-amylase and lysozyme were separated when the pH of the aqueous protein solution lay between the pIs of the proteins. In comparison with conventional electrophoresis, the migration direction was reversed and the migration speed increased between 100 and 1000 times.