Abstract： Objective To study the diagnostic and prognostic value of procalcitonin (PCT)in patients with sepsis in early stage. Methods In the perspective study, 168 patients enrolled were classified into three groups,ncluding 31 cases in control group,37 cases in SIRS group and 100 cases in general sepsis group. The latter were com-posed of moderate sepsis sub-group with 36 cases, severe sepsis sub-group with 40 cases and septic shock sub-group with 24 cases. Indexes of inflammation, SOFA and concentration of PCT in all patients were determined and their cor-relation with sepsis prognosis was analyzed. Results The level of PCT and CRP is 3.1 ± 2.3 μg/L and 34.7 ± 28.0 mg/L in SIRS group,is 10.8 ± 8.1 μg/L and 106.8 ± 69.3 mg/L in general sepsis group respectively. Which are higher than the level of PCT (0.3 ± 0.2 μg/L )and CRP (4.1 ± 2.9 mg/L)in control group (P < 0.01 ). Higher con-centration of PCT and CRP were found in general sepsis groups than these in SIRS group. The difference is prominem.Moreover,an increasing trend of PCT with the more serious of illness was found in subgroup analysis ,but not in CRP.According to the receiver operating characteristic curves( ROC curves) ,The best cutoff values in the diagnosis of sep-sis were >4.395 μg/L for PCT,>51.8 mg/L for CRP and >4.0 for SOFA score. Condusion PCT and CRP are useful diagnostic parameters with high specificity in early sepsis. PCT combining with SOFA score can be used as ide-al quantitative index to estimate the severity of sepsis and prognosis in patients with sepsis.