Abstract: Objective To explore the value of serum procalcitonin (PCT) and C reactive protein (CRP) detection in the diagnosis of community acquired pneumonia (CAP). Methods The serum PCT and CRP levels in 150 cases of CAP patients and 150 healthy subjects were determined. Results The serum PCT and CRP contents in patients with CAP were significantly higher than that in the normal controls (P <0.05). The sensitivity of PCT and CRP were 87.3% and 83.3% without significant differences (P>0.05); but the specificity of PCT and CRP were 95.3% and CRP 70.7% with significant differences (P<0.05). Conclusion The serum PCT and CRP determination has certain application value in the diagnosis of CAP. The serum PCT has superior sensitivity and specificity, and might be a better index in the differential diagnosis of community acquired pneumonia.