Some anti-snake venom Chinese herbs were used to test the antagonizing effect on ET-1 and S6b. Oral administration has shown that both the water and alcohol extracts from Cissus assamica and Aristolochia fordiana, and the water extracts from Desmodium microphyllum, Cynanthum paniculatum and Polygonum cillinerve are very helpful in reducing the acute death caused by ET-1 and S6b(i.v.), while the extracts from Cissus assamica, Aristolochia fordiana and Cynanthum paniculatum can dilate the vasoconstriction by ET-1 in a dose dependent manner. Pharmacodynamic parameters have shown that the potencies of alcohol extracts from Cissus assamica and Aristolochia fordiana are greater than that of Cynanthum paniculatum. These data suggest that traditional anti-snake venom herbs have antagonizing effects on ET-1.