Micellar Electrokinetic Capillary Chromatography employs electroosmotically pumped micellar mobile phases to achieve very efficient separations, A mixture of 14 modified nucleic acid components can be separated with 0.0081 and 0.075 M sodium dodecyl sulfate in phosphate/borate buffer, 10 kv of separation voltage, and a 68.5 cm x 0.06 mm I.D. fused-silica capillary lubing. Efficiencies in excess of 100,000 plates/m are routinely attained. The comparison between this technique and High Performance Liquid Chromalography is discussed in terms of column efficiency.