ObjectiveTo evaluate the value of serum procalcitonin (PCT) in diagnosis of infectious diseases in children at an outpatient department.MethodsSerum PCT value of 166 children with fever (98 in bacterial infection group, 68 in nonbacterial infection group) and 60 healthy children (control group) were detected by semiquantitative solid phase immunoassay， and blood routine test and Creactive protein (CRP) were also detected simultaneously, results of three groups were compared.ResultsIn bacterial infection group, the positive rates of PCT,CRP,white blood cell (WBC)count, and percentage of neutrophils were 92.86%（98 cases）,88.78%（87 cases）,86.73%（85 cases）,and 81.63%（80 cases） respectively, which were significantly higher than those of nonbacterial infection group(10.29%［7 cases］,27.94%［19 cases］,25.00%［17 cases］, 26.47%［18 cases］)and control group(6.67%［4 cases］,5.00%［3 cases］,8.33%［5cases］, 11.67%［7cases］) respectively (P＜0.01). Sensitivity (92.86%), specificity (89.71%) and Youden’s index (82.56) of serum PCT detection of bacterial infection group were all higher than those of CRP（88.78%,72.06%,60.84 respectively）and WBC（86.73%,75.00% and 42.30 respectively） and percentage of neutrophil (81.63%,73.53% and 55.15 respectively）.ConclusionPCT can be used as an indicator of the rapid diagnosis of early bacterial infection in children, and is with better sensitivity and specificity than the other inflammatory markers.