Objective: To evaluate the antimicrobial activity of nine plants of Polygonaceae in vitro. Method: Disc diffusion methods and porous plate methods were used to evaluate the inhibitory activity of different extracts of nine Polygonaceae plants against Staphylococcus aureus (SA)

Methicillin-resistant Staphylococcus aureus (MRSA) and ESBLs-SA. Result: The results indicated that methanol extract of Polygonum capitatum D. Don and ethyl acetate extract of P. capitatum at the concentration of 50 g·L-1 had a larger inhibiting diameter than that of other extracts of plants

among them MIC in the ethyl acetate extract of P. capitatum against SA

MRSA and ESBLs-SA was 0.062 5 g·L-1. The ethyl acetate extract of P. hydropiper L. var hispidum (Jook. F.) Steward. showed the highest inhibitory effect (IC50 0.45 g·L-1) in porous plate methods. Conclusion: Results showed that nine plants extracts of Polygonaceae have better inhibitory activity against the tested bacteria

especially P. capitatum and P. hydropiper L. var hispidum (Jook. F.) Steward. showed more significant antimicrobial activity.