Although nosocomial pneumonia in non-ventilated patients continues to be frequent and have high mortality rates, knowledge of the associated risk and prognostic factors is still limited. This retrospective study was designed to analyze epidemiological characteristics, risk and prognostic factors in patients with nosocomial pneumonia admitted to a hospital internal medicine department. Data on epidemiological, clinical and microbiological factors as well as diagnosis and clinical course were obtained from the medical records of 104 patients diagnosed with nosocomial pneumonia, according to Centers for Disease Control criteria, and from 104 control subjects. The incidence of nosocomial pneumonia was 18.8 per 1000 admissions. Risk factors significantly associated with contracting the disease were female sex, hospital stay longer than 14 days, other admission in the previous month and use of antibiotics during the previous six weeks. The most frequent underlying diseases were cardiorespiratory in nature (59.4%). Prognostic factors significantly associated with increased mortality were serious underlying disease, initially critical clinical status, severe and moderate respiratory insufficiency and bilateral radiological signs. More epidemiological data are needed to improve the diagnosis, treatment and prevention of nosocomial pneumonia.