True vocal cord paralysis may follow endotracheal intubation and be the result of peripheral nerve damage. This damage can occur as the result of compressing the nerve between an inflated endotracheal tube cuff and the overlying thyroid cartilage. A series of anatomic dissections defined the likely site of injury to be at the junction of the vocal process of the arytenoid cartilage and the membranous true vocal cord approximately 6 to 10 mm below the level of the cord. Cuff pressures were monitored during anesthetics. Analysis of the results indicated that nitrous oxide diffuses into endotracheal tube cuffs causing a substantial increase in the intracuff pressure. We have concluded that true vocal cord paralysis which follows endotracheal intubation is usually temporary. The solution to the problem lies in its prevention and several methods are described whereby it may be avoided.