A simple, accurate, precise, rapid and sensitive capillary zone electrophoresis (CZE) method was developed, optimized and validated for the simultaneous determination of strontium ranelate (antiosteoporetic drug) and aspartame (sweetener excipient) in pharmaceutical formulation for the treatment of postmenopausal osteoporosis. The final optimized conditions obtained were: borate buffer 50 mmol L-1 at pH 9.4 (BGE), applied potential of 30 kV, temperature set to 35 °C and hydrodynamic injection time of 10 s at a pressure of 50 mbar. The separation was carried out into a fused-silica capillary column (55 cm total length × 75 μm ID) and took less than 8 min. A diode array detector was used for the detection of the anion ranelate and aspartame at 235 and 198 nm, respectively. For both analytes, the method showed linear range from 1 to 40 μg mL-1, with satisfactory detectability (limits of detection of 0.3 and 0.2 μμg mL-1 for aspartame and ranelate, respectively). In addition, acceptable accuracy, good repeatability and intermediate precision (RSD < 2.6%) were obtained. The feasibility of the method was verified with recovery tests of analytes in the pharmaceutical sample. Recoveries varied from 85 ± 5% to 111 ± 2%, indicating the usefulness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]