A validated capillary zone electrophoretic method for analysis of sotalol is described. Analysis was performed in a fused-silica capillary with 20 mM phosphate buffer (pH 4.20) containing 10% (v/v) acetonitrile as background electrolyte. The applied potential was +20 kV, the injection time 0.08 min, signal detection was at 200 nm, and 3,4-dihydoxybenzylamine was used as internal standard. The method was validated over the concentration range 1.98 x 10(-5) to 9.90 x 10(-5) M; repeatability was good and there was no interference. Highly satisfactory results were obtained from analysis of tablets and serum, indicating the method is specific, accurate, and precise, and suitable for routine analysis of sotalol in pharmaceutical tablets and in pharmacokinetic studies.