The purpose of this study is to report 18 cases of membranous laryngotracheobronchitis (MLTB) and to review 143 published cases in order to accurately characterize the epidemiology, presentation, clinical course, treatment, and outcome of patients with this disorder. The male:female ratio was 2:1; mean age was four years. Most patients presented with acute onset of respiratory distress with fever, toxicity, and stridor after a prodrome of upper respiratory tract infection lasting a few days. White blood cell counts varied over a wide range, and blood culture results were rarely positive. Respiratory cultures commonly yielded Staphylococcus aureus or Haemophilus influenzae. Diagnosis was usually confirmed by airway radiographs or endoscopy. An artificial airway was required in 83% of patients. Complications included respiratory failure, toxic shock syndrome, anoxic encephalopathy, and death. MLTB is a serious, potentially fatal cause of acute infectious airway obstruction in infants and children that requires an organized approach to diagnosis and management.