Captopril, a new anihypertensive agent, has been assayed in authenitic as well as in tablet (Capoten((R))Manufacture: Squibb and Sons, Inc., Princeton, N.J., U.S.A. dosage forms by applying potentiometric visual, argentometric and oxidometric methods of idoine and cupric ion. Each method of assay involves the determination of captopril in a given weight of sample. Six samples were run for each method and the average percentages of recovery of captopril from its tablets were computed. For the potentiometric and visual silver methods the average percentages of recovery are 103.3 ± 1.2 and 102.3 ± 1.0 respectively. For the oxidometic methods of iodine and cupric ion, the average percentages of recovery are 103.8 ± 1.5 and 104.2 ± 1.4 respectively.