A capillary zone electrophoretic method with diode array detection was developed and validated for the determination of rosuvastatin calcium in pharmaceutical formulations. Using fused-silica capillary (i.d. 50.0 mu m, total length 48.5 cm and effective length 40.0 cm), the influence of the buffer composition, buffer pH and buffer concentration, as well as organic modifier, applied voltage, capillary temperature and injection time were investigated to optimize the method. Optimum results were obtained with 50.0 mM borate buffer at pH 9.5, capillary temperature 30 degrees C and applied voltage 25 W. The samples were injected hydrodynamically for 5 s at 50 mbar. Detection wavelength was set at 243 nm. Diflunisal was used as internal standard. The migration times of rosuvastatin calcium and diflunisal were 3.20 +/- 0.01 and 4.20 +/- 0.02. The total time of analysis was <6 min. The method was validated for rosuvastatin calcium determination in pharmaceutical formulations through following performance parameters: stability, linearity, sensitivity, precision, accuracy, recovery, selectivity, robustness and ruggedness. The linear calibration range was 3.00-200.00 mu g mL(-1) and the limits of detection and quantification were 1.00 and 3.00 mu g mL(-1) with RSD of 4.38 and 3.09%. The proposed method was applied for the determination of rosuvastatin calcium in its pharmaceutical formulation.