Sleep apnoea syndrome associated with maxillofacial abnormalities. Four cases with Obstructive Sleep Apnoea Syndrome (OSAS) are presented. They consisted of two cases with TMJ ankylosis with micrognathia, one case with Treacher Collins Syndrome, and one case with the Long Face Syndrome. Standard and specific cephalometric parameters were obtained to detect the site of the obstruction. Polysomnographic studies yielded information regarding the patient's sleep-wake state, respiratory and cardiac functioning, pre- and post-operatively. A temporary tracheostomy corrected the symptoms in one patient but the syndrome recurred when it was closed. Surgical correction of the maxillofacial anomalies will re-establish normal sleep patterns preventing OSAS. 