Purification of Puag-haad by extraction with diethyl ether and recrystalization in water yielded a compound proved to be 2, 4, 3, 5 -tetrahydroxystilbene dihydrate. A High Performance Liquid Chromatographic mathod measuring concentrations of 2, 4, 3, 5 -tetrahydroxystilbene in urine and plasma were developed. The method employs a one-step extraction procedure by using diethyl ether as a solvent followed by analysis on a reversed-phase high performance liquid chromatography on ..-bondapak C(,18)(10 um) with UV detection at 313 nm and 48% methanol in water (v/v) as a mobile phase. Phenacetin was used as an internal standard for quantitation. The detection limit for 2, 4, 3, 5 tetrahydroxystilbene in urine and plasma were 1.0 meg/ml (20 ng of the amount). in urine assay the mean recoveries were 92.3 % with 3.17 % coefficient of variaton and in plasma assay were 90.7 % with coefficient of variation of 2.52 % The method had been applied to the analysis of 2,4,3,5-tetrahydroxystilbene in urine and plasma following an oral dose of 3000 mg of purified Puan-haad to nine healthy male volunteers. This method was repid, specific and accurate and would be suitable for pharmacokinetic studies. 2,4,3,5-tetrahydroxystilbene kinetics were studied in nine healthy male volunteers, their mean age 33.2+5.2 years. Plasma levels and the cumulative of 2,4,3,5-tetrahydroxystilbene excreted in urine were determined by HPLC. Levels rose after drug administration reaching a miximum concentration of 0.702+0.347 mch/ml in 1.36+0.16 hr. The apparent absorption rate constant was 0.74+0.09 hr(-1). The mean area under the plasma concentration time curve was 2.5530+1.1439 hr.mcg/ml. The mean elimination half life was 0.96+0.11 hr corresponding to an elimination rate constant of 0.73+0.08 hr(-1). The mean renal clearance was 13.19+2.95 ml/hr/Kg. The detection of possible metabolite in urine by TLC method found only 2,4,3,5-tetrahydroxystill-bene. 2,4,3,5-tetramethoxystilbene and 2,4,3,5-tetraacetoxy-stibene were not detected. No side effect was reported by seven volunteers and only mild nausea was reported by two volunteers.