Abstract: Objective: To discuss the effects of early lactate clearance rate on the prognosis of patients with severe sepsis and septic shock. Methods: The lactic acid levels in 112 patients with severe sepsis and septic shock were measured at admission and at 6 hours of admission, and the lactate clearance rates of all cases were calculated. All patients were divided into the high lactate clearance rate group(the lactate clearance rate more than 10%) and low lactate clearance rate group(the lactate clearance rate less than 10%). The mortality, initial level of lactic acid and APACHE Ⅱ score between two groups were compared. All patients were followed up for 30 days, and divided into the survival group and death group according to their survival. The arterial blood lactate level, early lactate clearance rate and APACHE Ⅱ score between two groups were compared. Results: The difference of the initial level of lactic acid between the high lactate clearance rate group and low lactate clearance rate group was statistically significant(P<0.01). The mortality and APACHE Ⅱ score in high lactate clearance rate group were significantly lower than those in low lactate clearance rate group(P<0.01). Fifty-five cases died and 67 cases survived after 30 days of following up. The APACHE Ⅱ score in survival group was significantly lower than that in mortality group(P<0.01). The lactate clearance rate in survival group in the early period was significantly higher than that in mortality group(P<0.01). Conclusions: The early lactate clearance rate is an important index and more reliability in judging the prognosis of patients with severe sepsis and septic shock.