Objective To investigate the anti-coagulation mechanism of Hirudo extract on the release of thromboxane B2 (TXB2) and 6-keto-prostaglandin FI = (6-keto-PGF1α ) induced by thrombin from cultured human umbilical vein endotheliai cells (HUVECs). Methods The HUVECs were cultured in vitro. The well grown HUVECs of 2-3 generation were categorized into different kinds of groups : blank control group, thrombin-simulated group and groups of Hirudo extracts with low, medium and high doses. The raw drug concentrations of 150,300, and 600 mg/L of H...