ObjectiveTo evaluate the change and clinical significance of serum procalcitonin（PCT）and Creactive protein（CRP）in patients with septic shock. MethodsPatients with severe infection in the intensive care unit (ICU) of a hospital between January 2013 and June 2015 were selected. According to the extent of infection, patients were divided into septic shock group (n=66, subdivided into survival group ［n=50］ and death group［n=16］ according to 1month survival) and severe sepsis group (n=62), control group were patients without septic shock during the same hospitalization period, serum PCT, CRP, and WBC levels in each group at different times before and after treatment were compared. ResultsIn septic shock group, serum PCT，CRP and WBC levels before treatment, after 1, 3, and 7 days of treatment were all significantly higher than control group; in severe septic shock group, serum PCT and CRP levels after 1, 3, and 7 days of treatment were all significantly higher than control group; in death group, serum PCT levels after 1, 3, and 7 days of treatment were all significantly higher than survival group, CRP levels after 3 and 7 days of treatment were both significantly higher than survival group（all P<0.05）. Receiver operating characteristic (ROC) curves showed that area under the curve （AUC） and 95%CI of PCT，CRP, and WBC were 0.786（0.703-0.864），0.754（0.691-0.827），and 0.603（0.542-0.679） respectively. Spearman correlation analysis showed that serum PCT and CRP in patients with septic shock before treatment，after 7 days of treatment were positively correlated（［r=0.596，P=0.004］, ［r=0.523，P=0.012］, respectively）, and after 7 days of treatment, serum PCT was positively correlated with WBC（r=0.604，P=0.001）. ConclusionPCT can be used as a indicator in early diagnosis of patients with septic shock，and dynamic observation of PCT and CRP has important significance in evaluating patients’severity and prognosis.