Objective Evaluation of serum procalcitonin (PCT) in sepsis differential diagnosis and prognostic monitoring value.Methods 76 cases of sepsis patients,including 43 cases of early sepsis,severe sepsis patients in 20 cases,13 cases of patients with septic shock.Immunofluorescence is used on the detection of serum PCT and CRP levels.Results Septic shock group compared with severe sepsis,severe sepsis group compared with early sepsis group,PCT,CRP,APACHE Ⅱ was statistically significant (P ＜ 0.05) ; there is a significant positive correlation between sepsis patients serum PCT and APACHE Ⅱ score (r =0.57,P ＜ 0.05); after antibiotic treatment,serum PCT can be decreased rapidly,before discharge returned to normal levels,while the CRP after being controlled is still maintained at a high level,before discharge concentration was still higher than normal level,slowly than serum PCT.Conclusion For the identification of different degree of sepsis,PCT is a good index for monitoring the serum,also can make the sepsis prognosis.