A prospective study evaluated potential risk factors associated with laryngeal injury after prolonged endotracheal tube intubation for longer than 3 days. Ninety-seven patients were evaluated after oral endotracheal tube intubation (mean, 9 days). This study updates a previously reported evaluation of 44 patients. The additional sample size has provided findings of unreported patient risk factors of laryngeal injury and confirmation of previous associations. The majority of the 97 patients had some type of laryngeal injury, ranging from mild mucosal erythema to ulceration, granuloma formation, or true vocal cord immobility. Patient examinations were continued until the larynx returned to normal or stabilized or the patient was lost to follow-up. Postextubation examinations in the survival group revealed the following. (1) Laryngeal erythema occurred in 94%, and ulceration occurred in 76% of the patients with resolution within 6 weeks. (2) Laryngeal granulomas occurred in 44% of the patients; the majority of the granulomas (57%) developed an average of 4 weeks after extubation. Associated risk factors included duration of endotracheal tube intubation (p < 0.05) and presence of nasogastric tube (p < 0.05). (3) Vocal cord immobility was observed in 16 patients (20%). Eight patients had true vocal cord immobility noted initially after extubation, and the remaining eight had true vocal cord immobility an average of 4 weeks after extubation. Initial and delayed true vocal cord immobility were associated with duration of intubation and size of endotracheal tube (p < 0.01). Delayed true vocal cord immobility developed only in patients with a size 8 endotracheal tube.(ABSTRACT TRUNCATED AT 250 WORDS)