For the simultaneous detection of hydrochlorothiazide, hydralazine hydrochloride, and reserpine, a new stability indicating method was created in this work using the RP-HPLC method. Acetonitrile and potassium dihydrogen phosphate buffer were chosen as the mobile phases, while water:methanol (65:35) was used as the diluent. In spite of using other columns that had issues with retention duration, run time, and peak resolution for 7 minutes was used. used in this investigation. Final optimisation of the method resulted in optimised wavelength of the three drugs found at 235 nM.