Transport of critically ill children has become necessary following centralisation of paediatric specialist services. Children's Acute Transport Service (CATS) retrieves critically ill children in the Greater London area. Our teams have had to stop during these journeys to assist in road traffic accidents or ill passers-by. We undertook a review of our practice over a 3.5-year period. Our teams had to stop on 12 occasions over this period amounting to an incidence rate of 1 per 959 ambulance journeys. Although this is an infrequent occurrence, the impact on the retrieved patient and service delivery could be significant. We would like to direct the attention of transport services to this problem.