Three new spectrophotometric methods. Vierordt's method, its modified version and the absorbancy ratio method have been used for the simultaneous determination of hydrochlorothiazide and amiloride hydrochloride in binary mixtures. Mean recoveries, relative standard deviations and linearity ranges in calibration graphs of the methods were compared. These three methods have been successfully applied to a commercial pharmaceutical preparation, a sugar - coated tablet containing hydrochlorothiazide and amiloride hydrochloride.