OBJECTIVES: Nosocomial pneumonia (NP) is a costly and life-threatening complication of hospitalized patients. This study assesses the outcomes and costs associated with NP, specifically those with mechanical ventilation (MV) from the Belgian hospital perspective. METHODS: Data from the Belgian minimum basic data set from the first half of 2004 was used for this study. Patients from 37 hospitals with an ICD-9-CM code of bacterial pneumonia (481.xx-482.xx) and at least one IV antibiotic administration during their hospital stay were extracted. To isolate cases of pneumonia that were likely to be nosocomial, those with a secondary diagnosis of pneumonia and planned (versus emergency) admissions were retained. Outcomes for patients categorized on the basis of ICU stay and use of MV were assessed. Costs from the Belgian payer perspective were applied to resources utilized. RESULTS: The final analytical sample contained 441 admissions; 115(26%) with an ICU stay and MV (ICU+MV), 47(11%) with an ICU stay without MV (ICU Non-MV) and 279(63%) without ICU or MV (Non-ICU Non-MV). Approximately 74% were at least 65 years and 66% were males. Median length of hospital stay for the ICU+MV, ICU Non-MV and Non-ICU Non-MV groups were 32, 30, and 16 days. Total median hospital costs were €22,240, €14,565 and €14,793 for ICU+MV, ICU Non-MV and Non-ICU Non-MV respectively. Antibiotics formed a small part of the total cost: €972, €671, and €453 for ICU+MV, ICU Non-MV and Non-ICU Non-MV respectively. The ICU+MV group had the highest mortality (40%) compared to ICU Non-MV (26%) and Non-ICU Non-MV (24%). CONCLUSION: NP is a costly complication, with high mortality risks, specifically for patients with MV. This difference may be in part attributable to underlying pathogen differences, patient and pneumonia severity, or the appropriateness of anti-infective treatment choice. Further investigation is warranted to investigate the influence of these factors.