The aim of this study was to assess whether passive smoking affected the frequency of airway complications in children undergoing general anaesthesia. One hundred and twenty-five children undergoing general anaesthesia for elective daycase surgery were monitored for adverse respiratory events and desaturation during induction, intra-operatively and in the recovery room. Oxygen saturation was monitored throughout and a venous sample was taken for estimation of carboxyhaemoglobin levels. Parents were asked to fill in a questionnaire detailing their smoking habits. Sixty-three of the children were passive smokers with a potential daily exposure varying from 5-130 cigarettes. There was no difference in the frequency of respiratory events between passive smokers and those not exposed to cigarette smoke at induction or intra-operatively. However, in the recovery room, desaturation was significantly more common in passive smokers (p < 0.02). This was related to the cumulative number of cigarettes smoked by individuals to whom the child was exposed (p < 0.05). Neither carboxyhaemoglobin levels nor domiciliary address were predictive of desaturation. This study suggests that passive smoking contributes to postoperative arterial oxygen desaturation following general anaesthesia in children.