Duty of care is a fundamental aspect of nursing, and many nurses consider this to be an important part of their professional duties as a nurse. However, the legal underpinnings of duty of care are often overlooked, and, as such, nurses may be unsure about when to act if they encounter emergency situations or serious incidents, especially when they are off duty. This article examines the legal, ethical and professional aspects of duty of care, what these mean for nurses in practice, and how duty of care is intrinsically linked with standards of care and negligence.