Objective To study the predictive value of red blood cell distribution width in severity stratification of community-acquired pneumonia(CAP). Methods One-hundred and seventeen CAP patients admitted between August 2014 and August 2015 were recruited in the study.According to the severity of CAP evaluated by pneumonia severity index (PSI)and CURB score,the patients were divided into a severe group,a moderate group and a mild group with 39 cases in each group.Meanwhile 39 healthy volunteers were recruited as control.The blood red blood cell distribution width and high sensitive C-reactive protein(hs-CRP)levels were measured in all subjects. Results The PSI score and CURB score were significantly higher in the CAP patients than the control group and increased with the deterioration of the disease.The red blood cell distribution width and hs-CRP level were also significantly higher in the CAP patients than the control group and increased with the deterioration of the disease (P<0.05). Conclusion The red blood cell distribution width is correlated with the severity of CAP and has predictive value in CAP severity stratification.