Nosocomial pansinusitis (N P) is most often described in nasotracheally intubated patients with craniocerebral or facial trauma. We retrospectively reviewed its occurrence and complications in the course of prolonged mechanical ventilation in orotracheally intubated patients without maxillofacial or cranial injuries. N P was deemed to be present when (1) CT scan showed opacification and/or air-fluid levels in the maxillary, ethmoid and sphenoid sinuses and (2) aspiration of both maxillary sinuses yielded pus, cultures of which revealed a high concentration of micro organisms. Nosocomial pneumonia and bacteremia were considered related to the N P if the organisms found in the sinus were identical to those recovered from the blood and/or the bronchi. During an 18-month study period, 38 cases of sinusitis were diagnosed. N P was present in 13 patients: 18 organisms (12 Gram-negative, 5 Gram-positive and 1 Candida albicans) were isolated. Pneumonia occurred in 8 patients, 6 with multi-resistant Pseudominas aeruginosa and 2 with methicillin resistant Staphylococcus aureus. Pseudomonas aeruginosa was isolated from the blood, lung and sinus in two patients. This study demonstrates that N P is relatively frequent in patients requiring long-term mechanical ventilation, even in the absence of predisposing factors. N P in these patients is mostly monomicrobial with multi-resistant Pseudomonas aeruginosa and Staphylococcus aureus as the main causative agents.