When a patient does not or cannot drink or eat enough to maintain adequate hydration or nutrition, fluid with or without nutrients can be given through a tube. In law, a tube feed for an adult is regarded as a medical treatment that can be refused, withheld or withdrawn. Legal requirements and ethical principles of conduct are discussed in relation to a patient's ability or wish to drink and eat, and the administration of fluid with or without nutrients by tube. Emphasis is placed on adequate consultation from the outset with each competent patient, between all members of the health care team, and with those closest to an incompetent patient.