A revised edition of the guidelines of the Association of Anaesthetists of Great Britain and Ireland, for the pre-operative check of anaesthetic machines, was published in March 1997. A checklist based on the revised guidelines was used for the routine pre-operative checks of anaesthetic machines over a 6-week period in a district general hospital. One hundred and thirty-two checklists were completed. These were analysed for the time taken to complete the check and for the faults found in the anaesthetic machines. The mean time taken to complete a check was 6.8 min and the mean time taken to complete two consecutive checks, in the anaesthetic room and operating theatre, was 12.7 min. Carbon dioxide cylinders were present on the machines in 99 checks (75%), contrary to Association guidelines. Other faults were found in 40 checks (30.3%). The most frequent cause of faults was the oxygen analyser, faults being found in 15 checks. Other frequent faults were due to empty vaporisers or spare gas cylinders and the emergency oxygen bypass control.