The obstructive sleep apnoea syndrome (OSAS) is a common cause of morbidity during childhood. Although pediatric OSAS usually stems from adenotonsillar hypertrophy, it is also related to craniofacial anomalies. We report a case of extremely severe OSAS in a 5-year-old girl who has undergone adenoidectomy and partial tonsillectomy 1.5 year previously. A second adenotonsillectomy was elected to resolve abnormal respiration during sleep. Polysomnography was repeated 8 weeks after surgery and revealed an outstanding improvement but not complete resolution. The residual number of apnoeas is attributed to the retrognathia of the patient.