A capillary zone electrophoresis method is proposed for the purity determination of nine cephalosporin drugs. A background electrolyte comprising of either 20 mmol/L pH 9.20 borate buffer or 20 mmol/L pH 6.86 phosphate buffer was used for most drugs studied except for cefaloridine which formed neutral molecules at these pH values. For it 50 mmol/L pH 2.05 phosphate buffer was used instead. Internal normalization method was employed for quantitation. The method is simple, rapid and versatile. Analysis was completed within 8 min. The merits and limitations of the method were also discussed.