Abstract: The hydrochlorothiazide extracted from the urine by ethylacetate is dissolved inacetone. In the TLC, silica gel G is used as the adsorbent and the mixture ofbenzene-ether-acetone (3: 3: 4) is used as the developing solvent. The hydrochloro-thiazide spot, visualized under UV light in the chromatoplate, is eluted with absolute alcohol and determined at λ272nm by UV spectrophotometer. The recovery of hydrochlorothiazide from original spot and the spot after developing is 98.8% and 97.4% respectively. The total recovery of hydrochlorothiazide from the human urine accumulated in the period of 48 hrs after oral administration of this drug is 72.30%.