Introduction: Besides the improvement we have had in the diagnostic methods, the causative agent in around 50% of the cases of community-acquired pneumonia (CAP) remains unknown, even in inpatients. Despite that, adequate empirical therapy results in low mortality in the majority of the cases. Goals: To describe the epidemiology, the clinical presentation, the utility of diagnostic tests, the duration of hospital stay, the morbidity and mortality rates of 42 consecutive inpatients with CAP. Methods: The inclusion criteria were the presence of a recent pulmonar infiltrate in the CXR and two items out of fever (38ºC), productive cough and leukocytosis (> 10,000/mm3), in the presence of a compatible clinical syndrome. The subsidiary tests were performed as required on individual basis. Results: Forty-two patients, aged 64.7 ± 16.8 years, 27 (64.3%) male, were studied. Twenty-seven (64%) had subjacent illness. Seventeen (40.5%) were on antimicrobial therapy on admission. There were eight cases (19%) of severe pneumonia; the patients aged > 60 or £ 60 years were similar concerning the severity of presentation (p = 0.57) and had similar hospital stay (p = 0.25). The mean global hospital stay was 14.3 ± 7.6 days. Definite etiologic diagnosis were done in three patients: Legionella sp (2), S. aureus (1). In thirty-one cases (73.8%) the antimicrobial therapy wasn't modified; when it happened (11 patients, 26.2%), the main reason was the bad outcome in six cases (54.5%); in five (45.5%), the microbiological result prompted the change in therapy. Blood samples were drawn in 16 cases (38%), being positive in only one (6.3%). There were nine adequate sputum samples for analysis (9/22, 41%). There was only one death (2.4%), due to severe pneumonia in a patient with a neoplastic disease. Conclusion: The etiologic diagnosis in CAP is reached in a minority of cases, even in inpatients. At least partly, this is probably due to the previous use of antimicrobial drugs. Adequate empirical therapy results in low mortality. Diagnostic tests can be performed on individual basis.

Keywords: Pneumonia. Community acquired infections. Epidemiology. Therapeutics.