Abstract: 71 cases of nosocomialacquired Legionella pneumonia(NALP) and communityacquired Legionella pneumonia (CALP) were analyzed to improve the knowledge about them. The result showed that NALP and CALP were both frequent in male aged over 50, the clinical manifestation and chest radiographic finding were similar, the most frequent complication in both groups was respiratory failure. There were significant difference in risk factor, Legionella tape, mortality rate between NALP and CALP. Risk factors and mortality rate were higher in NALPgroup than in CALP. Legionella pneumophila in NALP is often LP₁、LP₆ and in CALPis LP₁₂.

Key words: legionella pneumonia, nosocomial infection, communityacquired pneumonia