The anatomical characteristic of the pediatric larynx allows physicians to better understand the incidence of symptomatic and severe presentations of acute laryngitis, which are frequent pediatric emergencies. Subglottis laryngitis and epiglottitis must be distinguished from each other. These two diseases are absolutely different: the first one is essentially viral and usually moderate, even though acute respiratory distress can occur. The other (epiglottitis) is bacterial, essentially caused by Haemophilus influenza B (Hi-B), and can be life threatening. The anti Hi-B vaccine leads to a decrease of frequency but does not make them disappear. Moreover, even if a child has a history of the Hi-B vaccine, diagnosis of epiglottitis can not to be ruled out. Lastly, in case of acute laryngeal dyspnea in a child, one must think about a foreign body.