Abstract: Objective To discover differences in risk factors of community acquired pneumonia and hospital acquired pneumonia and to provide the scientific basis for public health emergency control.Methods Pneumonia cases were collected consecutively in the First Hospital of Shanxi Medical University from May 2008 to October 2009.A total of 244 cases of pneumonia were collected with 178 cases of community acquired pneumonia and 66 cases of hospital-acquired pneumonia. Then risk factors were compared between the two groups.Results Univariate analyses showed that the two groups were significantly different in gender,age,education level,underlying disease,passive smoking,and history of exposure to respiratory tract infection.But there was no significant difference in occupation,smoking,drinking,and travel history.Multivariate analyses showed that the difference was significant in age,education level,underlying disease,and geographic distribution.Conclusion There are different risk factors between community-acquired pneumonia and hospital-acquired pneumonia and control measures should be taken in different ways.