The first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS) were analysed to compare anaesthetic incidents in infants and children with those in adults. Of the 2000, 1790 (90%) involved adults, 151 (7%) children and 56 (3%) infants. Healthy children (ASA I) generated a greater proportion of incidents in this group than adults and infants, emphasizing the need for maintaining the same standards for children in this group as for infants and higher risk groups. The AIMS results are similar to those of the United States (US) paediatric "closed claims" studies; the paediatric subset in both the US study and AIMS made up 10% of the total. Also, in both studies, incidents involving the respiratory and breathing circuit systems accounted for nearly half the problems, and cardiovascular problems and problems with the anaesthetic machine each accounted for 10-14% of incidents. In the AIMS study procedures on the head and neck yielded proportionately more incidents in the infant/child group than in the adult group, as did incidents involving the respiratory and breathing circuit systems. Incidents in the child group were often detected clinically; however, there were no differences between the three age groups in the way monitors were used or performed; hence the same monitoring recommendations apply to all groups. Combined oximetry and capnography would have detected nearly 90% of all applicable problems in the AIMS study and could have prevented nearly 90% of the claims arising from inadequate ventilation in the US "closed claims" study.(ABSTRACT TRUNCATED AT 250 WORDS)