An account is given of the 602 anaesthetic accidents reported to the Medical Defence Union of the United Kingdom over the eight-year period 1970-1977: these were reported from a total membership of 2,000 anaesthetists. It is known that reporting of minor accidents, for example damage to teeth, is very imcomplete, and that many deaths associated with surgery but due to disease processes rather than anaesthesia would not be reported either. It is thought, however, that the reporting by members of other accidents involving death and cerebral damage is likely to be complete, or nearly so. Cases of death and cerebral damage reported numbered 348 (60 per cent of the total) and the causes of these two major accidents were so closely similar that it was possible to deal with them together. This appears to be a suitable approach since cerebral damage can be as great, or greater, a catastrophe than death. In nearly half of this group of accidents there was discernibly faulty technique. Failure of postoperative care ( 10 per cent of the 348 cases) was another prominent and avoidable cause. Analysis of the faulty anaesthetic techniques which led to these major accidents showed that factors involved in tracheal intubation were preeminent, and that misuse of apparatus was also conspicuous. Over all error was deemed to be twice as common a cause of death and cerebral damage as was misadventure.