Abstract: Objective: The aim of the study was to measure the changes of mesentery lymph microcirculation and reactions to vascular active substances such as endothelin and prostacyclin in serious hemorrhagic shock rat. Methods: The rat model of serious hemorrhagic shock was made by bloodletting from common carotid artery. Movements and reactions of mesentery lymph microcirculation were observed with OLYMPUS SH 2 biologic microscope in 37 ℃ constant temperature box. The lymph were collected by intubating into chylocyst. The viscosity of lymph was measured by a viscometer. Results: Serious hemorrhagic shock led to a decrease of contractive frequencies and contractive ranges of mesentery lymph microcirculation, and a decrease in flux and viscosity of lymph. The reactions of mesentery lymph microcirculation to endothelin and prostacyclin were weaken. Conclusion: Serious failure of lymph microcirculation occurred in serious hemorrhagic shock rat. So improving lymph microcirculation is one of important treatments of serious shock.