Many junior doctors may not be aware that about one in 10 acute hospital admissions in the United Kingdom is associated with at least one adverse event, occasions on which patients are harmed by their medical management rather than the illness itself.1 2 About half of these adverse events are thought to be preventable, and a third are associated with serious disability or death. More commonly, less serious incidents cause inconvenience and discomfort for the patient and can lead to a longer stay in hospital—see the first scenario box about Mrs Jones (case scenario: part1). Junior doctors are at the front line of patient care and therefore play a crucial role in reducing harm to patients. This is why patient safety is an integral part of the Foundation Curriculum (www.foundationprogramme.nhs.uk).