By following the antihemostatic activity of the material according to Tajima's method, the antihemostatic principle was isolated from dried buds of Sophora japonica L., and identified as isorhamnetin [2-(3-methoxy-4-hydroxyphenyl)-3, 5, 7-trihydroxy-4H-1-benzopyran-4-one]. The antihemostatic specificity of isorhametin toward antihemorrhagic compounds isolated previously from hemostatic herbs used in traditional Chinese medicine was examined.