Of 97 patients with acute epiglottitis, 83 were reviewed retrospectively and 14 were studied prospectively to clarify some of the common misconceptions regarding the onset, clinical course, and management of this disorder. It is a relatively rare, life-threatening infection of infants and preschool-age children, but it also occurs in adults. It is frequently referred to as "Haemophilus influenzae croup epiglottitis," which is misleading, as croup is usually not present, and though H influenzae is the most common causative organism, other pathogens have been implicated. The course of acute epiglottitis is radically different from that of the more common viral croup syndrome in that the patients often have rapidly progressive and frequently abrupt airway obstruction. An assured airway is mandatory in treatment. Nasotracheal intubation should not be attempted without provisions for immediate surgical intervention. Acute epiglottitis should always be considered a surgical emergency. (JAMA 229:671-675, 1974)