This study was carried out to investigate inhibitory effect of extracts from root cortex of Paeonia suffruticosa on ${alpha}-glucosidase$ (EC 3. 2. 1. 20) and postprandial hyperglycemia. Methanol extract and organic solvent (n-hexane, ethyl acetate, butanol, aqueous) fractions from the crude drug were determined for the inhibitory activities against maltase, sucrase and ${alpha}-amylase$. The methanol extract from the crude drug strongly inhibited maltase (72%) and sucrase (76%) at the concentration of $100;{mu}g/ml$. Among the fractions examined, the ethyl acetate fraction from the natural plant drug showed potent inhibitory effects on maltase (85%) and sucrase (81%) at the concentration of $100;{mu}g/ml$. The ethyl acetate fraction from root cortex of Paeonia suffruticosa also exhibited significant reductions (21%) of blood glucose elevation in mice loaded with maltose.