Acquired upper airway obstruction is a common cause of respiratory emergencies in children. Most pathologic processes that result in upper airway compromise are a consequence of infection, trauma or aspiration. Today, many of the infectious causes of upper airway obstruction have lost their threat as a result of the progress made in preventing and treating these infections. Prompt recognition and appropriate management of the child presenting with upper airway obstruction remains critical, because certain causes can progress rapidly from a mild to a potentially life-threatening disease state. A correct diagnosis can often be made by history and physical examination, but additional studies may be useful in selected cases. The child’s clinical appearance is the most reliable indicator of severity, and measurable signs are of less value. If respiratory failure is imminent, airway protection and endoscopy for definitive diagnosis may have priority over any other therapeutic or diagnostic procedure.