A method is described for observing the pharyngeal airway in children with proven sleep apnoea using a flexible nasendoscope during light anaesthesia. Fifteen children were referred for endoscopic evaluation and treatment. All had documented obstructive sleep apnoea. Flexible endoscopic assessment of the airway revealed the site of obstruction in all cases and allowed a rational and successful management plan. The mechanism of obstructive sleep apnoea in infants and young children is discussed and the findings at endoscopy and results of treatment are reported.