Puerariae Radix (PR), the roots of Pueraria lobata (Leguminosae), is widely used in clinical Chinese medicine and also as a foodin oriental countries. PR is a rich source of isoflavones including puerarin, daidzin and daidzein. This study was aimed to compare theurinary kinetics of isoflavones between traditional decoction (TD) and concentrated powders (CP) of PR in healthy man. Ten male volunteerswere given two dosage forms of PR in a crossover design and their urine was collected at specific intervals until 36 h. Urine sampleswere assayed by an HPLC method before and after hydrolysis with β-glucuronidase and sulfatase. The results indicated that the parentforms of puerarin, daidzin and daidzein were not detected in urine, whereas daidzein sulfates/glucuronides were predominant, mainlysulfates. The half-lives of daidzein sulfates/glucuronides were 5 - 7 h. In conclusion, the isoflavones were exclusively metabolized tosulfates/glucuronides of daidzein following administration of TD and CP of PR. Through the comparison of urine kinetics between twodosage forms, we suggest that the standardization of the contents of daidzin and daidzein, which are bioavailable, is more importantthan puerarin content for the efficacy of PR.