Obstructive sleep apnoea (OSA) is defined as episodes of obstructive apnoeas and hypopnoeas during sleep with daytime somnolence. The gold standard in diagnostic tool patients with these symptoms is polisomnography. The goals of this study were to determine the frequency of OSA symptoms and the prevalence of OSA in patients undergoing operation. Patients were asked questions pertaining to symptoms of sleep apnoea. The patients who had two major symptoms or one major and two minor symptoms were invited to undergo a sleep study. Patients were diagnosed as OSA when they had apnoea–hypopnoea index higher than five. Forty-one patients with two major or one major and two minor symptoms of 433 patients were referred to the sleep laboratory. The most frequent major symptom was snoring, and the most frequent minor symptom was morning tiredness. In this connection, 18 (43.9%) patients accepted to be studied in the sleep laboratory (14 with two major, 4 with one major and two minor symptoms). Obstructive sleep apnoea was finally diagnosed in 14 patients or 3.2% of the initial entire population. Thirteen of them had two major symptoms, and only one of the 14 had one major and two minor symptoms. Six of the OSA patients were women. High percentage of OSA focus attention on anaesthesiology concerns of OSA. The exact management of each sleep apnoea patient with regard to intubation, extubation and pain control requires judgement and is a function of many anaesthesia, medical and surgical considerations. Therefore, we suggest that all patients should be asked for OSA symptoms, and patients with two major OSA symptoms must be evaluated with polisomnography.