Objective：To explore the relationship between procalcitonin and endotoxin in serum and the lung injury in rats with sepsis.Methods：Selected 45 cases of SPF m ale rats and randomly divided theminto the blank group，the shamoperation group and the modelgroup，15 cases in each group.Rats in the blank group did not get any intervention except for the routine feeding.Rats in the shamoperation group were sutured after removing the cecum and putting it back into the abdominal cavity.Rats in the modelgroup were established into anim almodels of sepsis by cecal ligation and puncture.Took blood and detected the levels of procalcitonin and endotoxin in serum through abdominal aorta after 6，12 and 24 hours respectively and then conducted correlation analysis by adopting Spearm an method.Results：Compared with those in the blank group，there was no significant difference being found in the comparisons of the levels of procalcitonin and endotoxin in serum as well as the value of PaO 2 and PaCO 2 at each time segment in the sham operation group( P ＞0.05).Compared with those in the blank group and the sham operation group，levels of procalcitonin and endotoxin in serum at each time segment in the modelgroup were significantly increased( P ＜0.05)；the value of PaO 2 at each time point was decreased( P ＜0.05)；the value of PaCO 2 at each time point was increased( P ＜0.05).Spearm an analysis show ed that the procalcitonin and endotoxin in serum were negatively correlated with PaO 2 in rats with sepsis( r =-0.458， r =-0.671， P ＜0.05)，and that the procalcitonin and endotoxin in serum were positively correlated with PaCO 2 in rats with sepsis( r =0.623， r =0.564， P ＜0.05).Conclusion：The higher the level of procalcitonin and endotoxin in serumin rats with sepsis，the more serious the injury of the lung function of rats.