Abstract
Yarrow (Achillea mille/olium Aggregat) is traditionally used against bleeding. Aqueous hot extracts were turbid and shortened the recalcification time, a global test ofthe blood coagulation. The residue obtained by membrane filtration of these extracts was the active fraction. This residue is problably located mostly in the stem. By pressure obtained juice elongated the blood coagulation. Compared with non-flowering and wilthed material, the blooming herb showed best effects. The storage conditions had no effect on the activity ofthe herb.