While medication errors during paediatric resuscitation are considered common, little information about the processes that contribute to them has been gathered. This prospective observational study in a large English teaching hospital describes the incidence, nature and severity of medication errors made by 15 teams, each comprised of two doctors and two nurses, during simulated paediatric resuscitations. Clinically significant errors were made in 11 of the 15 cases, most due to discrepancies in drug ordering, preparation and administration. The authors recommend additional research into new approaches to protecting patients in paediatric emergency settings.