Most acquired laryngeal stenoses in infants and children can be treated surgically with successful outcome. We describe two patient cases in which removal of such a stenosis did not result in decanulation, because another, hidden obstruction was present. This demonstrates the importance of preoperative assessment to indicate factors that influence the outcome of surgery, especially in infants with a syndrome. Guidelines for preoperative management and an extensive list of syndromes in which a hidden obstruction can be suspected, are presented.