The effect of intestinal lymph on blood pressure in rats was observed by the methods of lymph drainage and lymph infusion. The results obtained are as follows: (1) After 150 min of the lymph drained through the cannula of intestinal lymph duct, the blood pressure was significantly lower than that of the sham group (P < 0.05). (2) Equivalent albumin or intralipid infusion was not able to prevent the decrease in blood pressure when the lymph was lost. But in jugular-intestinal lymph duct shunt group, no significant blood pressure decrease could be seen during the drainage procedure for 4 h. (3) The blood pressure of rat with serious hemorrhagic shock could be increased significantly with a little amount of intestinal lymph infusion, and the rats survived longer than those of the control group (P < 0.05-0.01). The above results suggest that the intestinal lymph may play an important role in maintenance of blood pressure, in addition to the known function of lymphatic system by returning tissue fluid to blood and maintaining circulating blood volume.