A simple and fairly fast capillary zone electrophoresis method has been developed for the determination and separation of ceftriaxone, ceftizoxime, paracetamol, and diclofenac sodium in a mixture, in pharmaceutical formulations, and in blood serum. A 50 mM sodium tetraborate background electrolyte solution (pH 9.0) was found to be suitable for separation of all the drugs. An uncoated fused-silica capillary of a total length of 57 cm (effective length 50 cm) was used for separation. All the analytes were completely separated within 8.0 min at an applied voltage of 30 kV and detection was performed at 214 nm. Validation of the method was performed in terms of linearity, accuracy, precision and limit of detection, and quantification. The linearity of the calibration curves for paracetamol was 5-125 mu g/mL, for ceftizoxime was 5-500 mu g/mL, for diclofenac was 1-125 mu g/mL, and for ceftriaxone was 10-1000 mu g/mL, while LOD of the paracetamol, ceftizoxime, diclofenac, and ceftriaxone was found to be 1.0, 1.0, 0.5, and 5.0 mu g/mL, respectively. The proposed method was applied for the determination of active ingredients in pharmaceutical formulations and active drugs in human blood serum. The recovery was found to be >= 99% with the relative standard deviation (RSD) <= 2.1% for both matrices.