Perforation of the hypopharynx or esophagus is a serious though not often reported complication of endotracheal intubation. Only 12 cases had been reported before the eight which are presented here to emphasize this hazard of intubation. The early symptoms of perforation, which occurred during insertion of the tube, were: subcutaneous emphysema (seven patients), mediastinal emphysema (six), pneumothorax (two), cardiac arrest (one). One patient had no recognized early signs of perforation, but presented with an abscess of the mediastinum six weeks later. The site of perforation, determined by endoscopy in six patients, was the lateral hypopharynx in four, and the vallecula in two. The outcome of the eight perforations was as follows: two patients recovered on conservative management; in two, abscesses of the neck and in one an abscess of the mediastinum developed. All three recovered after drainage of the abscesses. Three patients died. Two outstanding characteristics of these eight cases were that in all of them intubation was attempted by physicians relatively inexperienced in the technique, and in all but one it was done in emergency. Since the use of intubation in emergency situations is increasing, all physicians in training should receive formal instruction in technique.