This is a retrospective study of 500 cases of hospitalized patients with the diagnosis of croup (laryngotrachitis), admitted between January 1986 and August 1988, at the Montreal Children's Hospital. The patient's age, sex, clinical history, physical examination, number of admissions, season of admission, method of diagnosis, treatment and management were reviewed. Two per cent of these patients were diagnosed as bacterial croup. All of them required intubation and endoscopic evaluation in their management. Of all the viral croup patients, less than one-third were severe enough to require an intensive care setting for their management. In these patients, 6% required endotracheal intubation, and on endoscopy, a significant number of these patients had an endoscopic airway abnormality in addition to croup (subglottic edema). According to our findings, we suggest diagnostic micro-laryngoscopy and bronchoscopy be performed on certain groups of croup patients because of their higher yield of airway abnormality on endoscopy.