Learning in health care is essential if healthcare organisations are to tackle a challenging quality of care agenda. Yet while we know a reasonable amount about the nature of learning, how learning occurs, the forms it can take, and the routines that encourage it to happen within organisations, we know very little about the nature and processes of unlearning. We review the literature addressing issues pivotal to unlearning (what it is, why it is important, and why it is often neglected), and go further to explore the conditions under which unlearning is likely to be encouraged. There is a difference between routine unlearning (and subsequent re-learning) and deep unlearning--unlearning that requires a substantive break with previous modes of understanding, doing, and being. We argue that routine unlearning merely requires the establishment of new habits, whereas deep unlearning is a sudden, potentially painful, confrontation of the inadequacy in our substantive view of the world and our capacity to cope with that world competently.