The sleep apnoea syndrome is reviewed, defined, and classified. Particular emphasis is placed on the identification of a patient population that is prone to sleep apnoea and the diseases and syndromes that are associated with it. For anaesthetists, direct enquiry into daytime and nighttime sleep abnormalities and careful examination of the upper airway are important for preoperative detection of these patients and especially patients with obstructive sleep apnoea who might present for anaesthesia and operation. A typical case is reported and details of the preoperative, peroperative and postoperative management are discussed.