Two methods of oxygen delivery were compared when used postoperatively after a general anaesthetic had been administered. There were 255 patients randomly allocated to receive oxygen via nasal spectacles or a Hudson face mask in the initial postoperative period. Oxygen saturation was monitored using pulse oximetry. Seven percent of patients who received the Hudson mask and 14% of patients who received nasal spectacles desaturated below 94% (P = 0.10). Age, weight or American Society of Anesthesiologists (ASA) status did not predict oxygen desaturation; however, desaturation occurred more frequently in male patients with nasal spectacles undergoing abdominal surgery. If male patients who had abdominal surgery with muscle relaxants are excluded from the nasal spectacle group, the desaturation incidences for spectacles and masks are similar (10% versus 7%, P = 0.38). Using nasal spectacles for all postoperative oxygen therapy in selected patients is therefore feasible and could provide substantial cost-saving.