It is an established principle that nurses owe their patients a duty of care, which incorporates a legal, an ethical and a professional duty. However, they must also meet the standard of care deemed necessary to maintain safe and effective delivery of care to patients. Defining what is meant by the standard of care is complex, and meeting it can be challenging in an increasingly pressurised healthcare environment. This article describes the standard of care required using previous legal cases. It also explores some of the challenges involved in defining the standard of care in a rapidly changing healthcare environment.