Objective:To investigate the value of C-reactive protein(CRP) for differential diagnosis of infectious and non-infectious fever.Methods:552 patients with initial diagnosed as fever of unknown were enrolled in this study.CRP was determined within the first 24h of hospitalization by immune turbidimetry.The ROC and area under the curve were used for analyses the differential diagnosis value.Results:412 patients were diagnosed as infectious fever in 552 patients(74.6%);140 patients as non-infectious fever(25.4%).The CRP in infectious fever group were higher than that in non-infected group(t=14.257

P=0.000 1).The area under ROC for CRP diagnosis of infectious fever was 0.752

95% of the CI

0.650～0.854.The cut-off value was 8 mg/L with the sensitivity

specificity

accuracy

positive predictive value

negative predictive value

positive likelihood ratio and negative likelihood ratio were 90.3%

68.6%

84.8%

89.4 %

68.6%

2.88 and 0.14

respectively. Conclusion:CRP test can identify fever with infection or non-infectious;It should be timely antibiotics when CRP ≥ 8mg/L.