AbstractGiven advances in the science of fertility preservation and the link between fertility choices and wellbeing, it is time to reframe our ethical thinking around fertility preservation procedures for children and young people with cancer. The current framing of fertility preservation as a possible offer may no longer be universally appropriate. There is an increasingly pressing need to discuss the ethics of failing to preserve fertility, particularly for patient groups for whom established techniques exist. I argue that the starting point for deliberating about a particular patient should be a rebuttable presumption that fertility preservation ought to be attempted. Consideration of the harms applicable to that specific patient may then override this presumption. I outline the benefits of attempting fertility preservation; these justify a presumption in favour of the treatment. I then discuss the potential harms associated with fertility preservation procedures, which may justify failing to attempt fertility preservation in an individual patient's particular case. Moving from a framework of offer to one of rebuttable presumption in favour of fertility preservation would have significant implications for medical practice, healthcare organizations and the state.