OBJECTIVE:To investigate the effects of different processed products of Paeonia lactifloria in Shaoyao gancao tang on the content of paeoniflorin in their use.METHODS:The content of paeoniflorin in Shaoyao gancao tang was determined by HPLC in which SHIMA-DCIS ODS C18 was used as chromatographic column with acetonitrile-0.1% phosphoric acid water solution(15∶85) used as a mobile phase at a flow rate of 1.0 mL?min-1.The detective wavelength was set at 230 nm.RESULTS:In Shaoyao gancao tang,the content of paeoniflorin in Radix Paeoniae Rubra was the highest,followed in descending order by Radix Paeoniae Alba Prepara cum Vini,Radix Paeoniae Alba Prepara Flava,Radix Paeoniae Alba sine Cortice and Radix Paeoniae Alba. CONCLUSION:The difference in the content of paeoniflorin appeared when Radix Paeoniae Rubra,Radix Paeoniae Alba Prepara cum Vini and Radix Paeoniae Alba respectively used in combination with Shaoyao gancao tang suggest that Radix Paeoniae Rubra,Radix Paeoniae Alba and its processed products should be used differently based on different syndrome in clinical use of Shaoyao gancao tang.