Objective:To investigate the similarities and differences of etiology and clinical characteristics in the elderly health care associated pneumonia（HCAP）and community-acquired pneumonia（CAP）and hospital-acquired pneumonia（HAP）. Methods:The clinical data and sputum culture data of 152 cases of CAP and 102 cases of HCAP and 78 cases of HAP in our hospital were retrospectively analyzed. Data were analyzed using SPSS 17.0 statistical software and using analysis of variance and chi square test. Results:There was no obvious statistical significance difference in the general condition of three groups（P>0.05）. There were significantly differences in the lung rale

cough and difficulty breathing among three groups（P<0.05）;while the rale rate was 83.3%（125/152）and difficulty breathing rate was 38.2%（58/152）in CAP group

significantly lower than those of other groups（P=0.006

P=0.009）. There were significant differences among three groups in etiology aspects（P<0.05）. In CAP

the common strains of streptococcus pneumoniae[27.0%（41/152）] and haemophilus influenzae[19.1%（22/152）] were higher than those of other groups

and the pseudomonas aeruginosa [7.9%（12/152）] and fungi [2.0%（3/152）] were lower（P <0.01）. The detection rate of acinetobacter baumannii was 29.5%（23/78）

higher than those of other groups（P=0.000）. The mortality rates were 23.5%（24/102）in HCAP group

25.6%（20/78）in HAP group and 5.3%（8/152）in CAP group（P<0.01）. Conclusion:Clinical manifestation of senile pneumonia appears diversified and pathogenic bacteria is complicated. The clinical characteristics and prognosis of etiology and treatment in HCAP group have its own characteristics. High incidence of fungi and high mortality rate should be reasonable use for antibiotics and comprehensive therapy.