The aim of this study was to determine the incidence of laryngotracheal injuries following intubation and/or tracheotomy in intensive care unit (ICU) patients and to analyze their prognostic factors. This prospective study includes the clinical data and endoscopic exploration of 654 ICU patients who underwent oro-tracheal intubation between September 1992 and February 1999. The prognostic factors for upper airway injuries were analyzed using a multivariate statistical study. Endoscopic exploration of the upper airway 6 to 12 months after extubation revealed laryngotracheal injuries in 30 of the 280 patients examined (11%). The most important factors influencing the development of laryngotracheal lesions were the duration of the oro-tracheal intubation and the length of time in the ICU. Patients at high risk of developing injuries were those with pathological background, a non-neurological or non-surgical (medical) admission or upper-airway injuries at an early stage. The length of oro-tracheal intubation is the most important factor in the development of laryngotracheal injuries. Consequently, it is essential to establish a time limit to perform tracheotomy in ICU patients. Such timing should be adapted to each patient and pathology.