TWO SIMPLE, accurate spectrophotometric and potentiometric m methods were developed for the determination of cefprozil, dropropizine and tizanidine hydrochloride in their pharmaceutical preparations. The spectrophotometric method is based on the selective oxidation of cefprozil or tizanidine with N-bromosuccinimide in an alkaline medium to give an intense yellow product with a maximum absorption at 396 or 384 nm, respectively. The reaction conditions were studied and optimized. The reaction obeyed Beer's law over the concentration range 5-40 and 10-80 g ml-1 for cefprozil and tizanidine hydrochloride, respectively. The potentiometric method involves the direct titration of cefprozil and dropropizine with N-bromosuccinimide in sulphuric acid medium and the end point is determined potentiometrically using platinum electrode. Cefprozil and dropropizine can be determined quantitatively in the concentration range of 0.13-1.30 and 0.118-1.180 mg with recovery values of 98.46-100.77 and 99.58-100.85% and relative standard deviations 0.39-0.54 and 0.52-0.87% for cefprozil and dropropizine, respectively. The proposed methods are applied for the determination of these drugs in pure forms and in pharmaceutical preparations.