Aim:To investigate the influence of dosage forms on the pharmacokinetics ofdaidzein and its main metabolite daidzein-7-O-glucuronide in Wistar rats.Methods:After administration of two typical dosage forms(daidzein solution andsuspension),the concentrations of daidzein and daidzein-7-O-glucuronide weredetermined by an LC-MS-MS method.The pharmacokinetic parameters were cal-culated and analyzed statistically using the Student’s t-test.Results:Absorp-tion of daidzein after administration of daidzein solution(t_(max)=0.46 h)was morerapid than that of the suspension(t_(max)=5.00 h).The peak plasma concentrationsof daidzein after administration of daidzein solution and suspension were 601.1 μg/Land 127.3 μg/L,respectively,and those of daidzein-7-O-glucuronide were 3000 μg/Land 192.6 μg/L,respectively.The absolute bioavailabilities of free daidzein in ratsafter administration of daidzein solution and suspension were 12.8% and6.1%,respectively,which were calculated to be 47.0% and 12.2%,respectively,inthe form of total daidzein(free plus conjugated daidzein).Conclusion:Absorp-tion of daidzein solution was better than absorption of suspension(P<0.05). Aim: To investigate the influence of dosage forms on the pharmacokinetics of daidzein and its main metabolite daidzein-7-O-glucuronide in Wistar rats. Methods: After administration of two typical dosage forms (daidzein solution andsuspension), the concentrations of daidzein and daidzein- 7-O-glucuronide were determined by an LC-MS-MS method.The pharmacokinetic parameters were cal-culated and analyzed statistically using the Student’s t-test. Results: Absorption of daidzein after administration of daidzein solution (t_ (max) = 0.46 h) was morerapid than that of the suspension (t_ (max) = 5.00 h) .The peak plasma concentrations of daidzein after administration of daidzein solution and suspension were 601.1 μg / Land 127.3 μg / L, respectively, and those of daidzein-7 -Oglucuronide were 3000 μg / Land 192.6 μg / L, respectively. The absolute bioavailabilities of free daidzein in rats after administration of daidzein solution and suspension were 12.8% and6.1%, respectively, which were calculated to be 47.0% and 12.2% , re spectively, inthe form of total daidzein (free plus conjugated daidzein) .Conlusion: Absorption of daidzein solution was better than absorption of suspension (P <0.05).