Abstract: Objective:To investigate the value of serum procalcitonin(PCT) and C-reactive protein(CRP) in the diagnosis of interstitial lung disease complicated with infection.Methods:A total of 98 patients with interstitial lung disease were divided into the infection group(54 cases complicated with infection) and uninfection group(44 cases complicated without infection).The serum levels of CRP,PCT,white blood cells(WBC),and neutrophil percentage(N%) were measured in two groups.Results:The differences of the levels of serum PCT and CRP between two groups were statistically significant(P<0.01),and the differences of the level of WBC and N% between two groups were not statistically significant(P>0.05).Correlation analysis showed that the levels of PCT and CRP were positively correlated with infection in patients with interstitial pneumonia(P<0.01 and P<0.05).The area under the ROC curve of the CRP and PCT in diagnosing interstitial pneumonia was significantly higher that of WBC and N%(P<0.01).Conclusions:The clinical value of PCT and CRP in the diagnosis of patients with interstitial lung disease complicated with infection is high,which can effectively judge the infection situation of patients with interstitial lung disease,and is worthy of promotion.