Objective:To investigate the diagnostic value of calprotectin for sepsis.Methods:We prospectively enrolled adult patients who were transferred to intensive care unit(ICU)after surgery.205 patients after surgery were included in this study. There were 100 patients in the sepsis group and 105 patients in the non-sepsis group. Venous blood samples were collected from all patients within 24 hours after admission to ICU. We also collected venous blood samples from patients in the sepsis group within 24 hours after diagnosis of sepsis. Then calprotectin levels were measured. We compared baseline data and laboratory indexes between the two groups immediately after enrollment. Risk factors of sepsis were evaluated by univariate and multivariate Logistic regression analysis. We drew ROC curve of calprotectin for sepsis diagnosis to evaluate its diagnostic value.Results:The sepsis group had significantly higher serum levels of calprotectin and PCT than the non-sepsis group(P<0.01). Multivariate logistic regression analysis revealed that SOFA score, emergency surgery, diabetes, serum calprotectin, PCT and white blood cell were independent risk factors for sepsis after major surgery. The AUC of calprotectin for diagnosing sepsis after major surgery was 0.81(95% CI 0.75, 0.86), and that of PCT was 0.78(95% CI 0.71, 0.84). The AUC of calprotectin combined with PCT for diagnosing sepsis after major surgery was 0.87 (95% CI 0.81, 0.92).Conclusions:Plasma calprotectin is a diagnostic marker for sepsis after surgery, and its early diagnostic value is higher when combined with PCT.