Objective To analyze the serum level of procalcitonin (PCT) in children with bacte-rial or viral pneumonia, explore its diagnostic value in diagnosis of bacterial pneuminia in children, and so as to provide evidence for clinical use of antibiotics. Methods A total of 42 children with pneumonia(mean age was 5.6 yrs, including 24 boys and 18 girls) were divided into viral neumonia group (n=25) and bacterial neumonia group (n=17). Semi-quantitative solid-phase immunoassay was applied to measuring serum procalcitonin. There were four PCT grades:<0.5 ng/mL,≥0.5 ng/mL,≥2 ng/mL and≥10 ng/mL. X2 test was performed. Results The serum level of PCT was more elevat-ed in bacterial neumonia group than that of viral neumonia group, and the difference was statistically significant (P<0. 01). Conclusion As a sensitive marker of bacterial pneumonia in children, serum procalcitonin contributes to diagnosis and differential diagnosis of pneumonia in children, which may provide basis for clinical use of antibiotics.