Voluntary anonymous reporting of incidents which occur during anaesthesia is a mechanism for obtaining information about such problems. Our objective was to estimate with reporting such incidents. For 3 months, alongside the incident report form, another form, which had to be completed for every patient, was used. This form listed a series of defined events which could occur intra-operatively. Compliance with the incident reports was estimated by comparing the data obtained from the two sets of forms. Overall compliance was only about 30%. There were differences in compliance for different events. Compliance was high with more serious events and poor in the case of common events, or when successful recovery had occurred. In order to improve compliance, incident report forms should be available on each anaesthetic machine and staff should be made more aware of the fact that reportable incidents are not limited to events which harmed the patient, but also include those which could have affected patient safety.