Trained anaesthetic assistants are considered essential for the safe conduct of anaesthesia. Data from 5837 AIMS (Anaesthetic Incident Monitoring Study) reports were evaluated for issues concerning anaesthetic assistants in the generation and resolution of anaesthetic incidents. "Inadequate assistance" as a contributing factor was identified in 187 reports, whilst "skilled assistance" which minimized the incident was present in 808 cases. One hundred and seventy-two reports specifically commented on anaesthetic assistants in the narrative section of the AIMS form. All surgical specialties were represented. In 147 of these reports the assistant actually contributed to or failed to assist with the incident. Although the majority of outcomes from the reports were uneventful, prolonged stay, awareness and ICU admission did ensue in a small number of cases. The most common incidents were related to problems with equipment, communication and inadequate staffing levels (number and/or skill mix). Results from this study have implications for anaesthetic assistant staffing levels and the orientation of course content.