N No os so oc co om mi ia al l a an nd d c co om mm mu un ni it ty y--a ac cq qu ui ir re ed d L Le eg gi io on ne el ll la a p pn ne eu um mo on ni ia a: : c cl li in ni ic ca al l c co om mp pa ar ra at ti iv ve e a an na al ly ys si is s Patients in the nosocomially acquired Legionella pneumonia (NALP) group were older than those in the community-acquired Legionella pneumonia (CALP) group. Univariate analysis showed that smoking habit, cough, thoracic pain, and extrapulmonary manifestations were more prevalent in the CALP group, whilst chronic lung disease and cancer were more prevalent in the NALP group. Moreover, patients in the NALP group were more likely to have received oxygen and corticosteroid therapy and also to have altered creatinine values than patients in the CALP group, whilst more patients in the latter group had altered alanine aminotransferase values. However, multivariate analysis failed to confirm most of these differences. Smoking habit and blood creatinine levels were the only variables remaining significant.In conclusion, demographic, clinical, laboratory, radiological and outcome data in nosocomial and community-acquired Legionella pneumonia are quite similar.