The first 2000 incidents reported to the Australian Incident Monitoring Study were analysed with respect to the incidence and circumstances of problems with endotracheal intubation; 85 (4%) indicated difficulties with intubation. One third of these were emergency cases, one third involved an initially unassisted trainee and one fifth were outside normal working hours. Failure to predict a difficult intubation was reported in one third of the cases, with another quarter presenting serious difficulty despite preoperative prediction. Difficulties with ventilation were experienced in 1 in 7 of the 85 reports; there was one cardiac arrest, but no death. Endotracheal intubation was not achieved in one fifth of the cases. The commonest complications reported amongst the 85 incidents were oesophageal intubation (18 cases), arterial desaturation (15 cases), and reflux of gastric contents (7 cases). Emergency trans-tracheal airways were required in 5 cases. Obesity, limited neck mobility and mouth opening, and inadequate assistance together accounted for two thirds of all the contributing factors. The most successful intubation aid in this series was a gum elastic bougie. A capnograph contributed to management in 28% and a pulse oximeter in 12% of the cases in which they were used. The most serious desaturations were associated with accidental oesophageal intubation. These data suggest a lack of reliable preoperative assessment techniques and skills for the prediction of difficult intubations. They also suggest the need for a greater emphasis on ensuring that the necessary equipment is available, and on teaching and learning drills for difficult intubation and any associated difficulty with ventilation.