Abstract: The dissolution rate of three brands of hydrochlorothiazide tablets was studied in simulated gastric and intestinal medium by using basket and circulating flow methods. The tablets used were two brands of home-made tablets (25 mg) and Merck Sharp and Dohme tablets ( 25 mg). The results showed that the parameters of T_(50),T_d, and m (slop) of tablets were significant difference statistically (P<0.01), but for the time of releasing 60% of hydrochlorothiazide, all three brands of tablets were less than 30 min., this dissolution rate meets the specification of USP XIX