Abstract: Objective To preliminarily explore the role of serum procalcitonin (PCT) quantization in differntiating coagulase-negative staphylococci (CNS) blood stream infection and contamination derived from blood culture in children. Methods Clinical data of 83 cases of CNS derived from blood culture in People’s Hospital of Changning city, Hunan province between January, 2013 and December, 2013 were retrospectively reviewed. The cases were divided into blood stream infection group and contamination group. The basic demographic characteristics, origins of patients, C reactive protein, time to positivity of blood culture (TP), procalcitonin were compared between the two groups, and the diagnostic performance of PCT according to the ROC curve were analyzed. Results Age, gender, C reactive pretein and TP showed no difference between blood stream infection group (n=38) and contamination group (n=45)(P>0.05), while the proportion of contamination of patients from medical wards was higher than that from surgery wards (P<0.05). PCT was significantly higher in blood stream infection group than that of contamination group (P<0.001). The diagnostic sensitivity, spectivity, accuracy of PCT in differentiating the two groups were 86.8%, 82.2% and 84.3%, respectively, at the best cutoff of 0.195 ng/ml. Conclusions PCT may be a good marker for differentiating CNS blood stream infection and contamination derived from blood culture in children, and may help clinicians make early and reasonable selection of antibiotics.