The chiral resolution of baclofen was achieved by capillary electrophoresis using a fused-silica capillary (60 cm x 75 mum ID). The background electrolyte (BGE) was phosphate buffer (pH 7.0, 50 mm)-acetonitrile (95:5 v/v) containing 10 mm beta-cyclodextrin. The applied voltage was 15 kV. The values of alpha and R-s were 1.06 and 1.00, respectively. The electrophoretic conditions were optimized varying the pH and the ionic strength of the BGE, concentrations of beta-cyclodextrin and acetonitrile and the applied voltage.