Abstract: Objective: To explore the clinical value of lactic acid and cystatin C(Cys C) in the evaluating of the condition and prognosis in patients with sepsis.Methods: The levels of lactic acid and Cys C and APACHEⅡ score in 83 patients with sepsis were detected on admission,the differences of which between the death group and survival group,between the sepsis group,severe sepsis group and septic shock group and between the APACHEⅡ score with less than 15 group,APACHEⅡ score with from 15 to 24 group and APACHEⅡ score with more than 24 group were compared.The correlations of lactic acid,Cys C and APACHEⅡ score were analyzed using Pearson.The predictive value of lactic acid and Cys C in the mortality of patients were evaluated by logistic regression analysis.Results: The levels of lactic acid and Cys C in death group were significantly higher than those in survival group(P<0.01).The levels of lactic acid and Cys C in septic shock group were higher than that in severe sepsis group(P<0.01 and P<0.05),the levels of lactic acid and Cys C in severe sepsis group were higher than that in sepsis group(P<0.01).With the rise of APACHEⅡ score,the levels of lactic acid and Cys C in patients significantly increased(P<0.01).The levels of lactic acid and Cys C were a positive correlation to APACHEⅡ score(P<0.05).The lactic acid and Cys C were the risk factors in predicting the prognosis of patients with sepsis.Conclusions: Lactic acid and Cys C can be used as the predictive parameters in the condition and prognosis in patients with sepsis.