Objective:To study the effects of Buyang Huanwu Decoction（BHD） and Astragalus mongholicus on in vitro platelet activating factor（PAF） receptor activity in the platelet of the rabbit.Methods:The study included three groups

whole BHD group

group of activating blood circulation and group of invigorating qi

and the specific binding inhibition rate of PAF receptor was determined with radioligand receptor binding method.Effects on in vitro PAF receptor activity in the platelet of the rabbit were compared among the three groups.Results:The specific binding of

3 H-PAF with PAF receptor in the platelet of the rabbit was inhibited in all the three groups

and the inhibiting degree was in the following order:group of activating blood circulation

>

whole BHD group

>

group of invigorating qi with significant differences among the three groups（P

<

0.01）.Conclusion:Single Astragalus mongholicus（120g） can inhibit the specific binding of PAF receptor in the platelet of the rabbit with

3 H-PAF

but combination of Astragalus mongholicus with the drugs for activating blood circulation in BHD can significantly decrease the inhibiting action of the latter on PAF receptor activity of the platelet

reflecting the combined mechanism of “ removing blood stasis without injuring the votal qi” in BHD.