The literature on complications of tracheal intubation is reviewed and a new classification is proposed for these complications. Incidents and accidents (early or immediate complications) are arranged in three etiopathogenic classes and in topographic subclasses, the status of endotracheal intubation being divided into three distinct periods: I: the act of intubation; II: the tube in place; III: extubation. Sequelae (late complications) are classified according to clinico-pathologic criteria. The etiologic factors of sequelae are divided into three groups: predisposing factors, adjuvant factors, and decisive or determinant factors. Possible prevention or remedy of many complications is presented.