Myocardial stunning refers to the contractile dysfunction that occurs following an episode of acute ischaemia, despite the return of normal blood flow. The phenomenon was initially identified in animal models, where it has been very well characterised, and there was initial doubt about whether a similar syndrome occurred in humans, and if it did, whether it was of any clinical relevance. This article outlines the conditions that must be met to diagnose myocardial stunning and why it has been difficult to confirm its presence in humans. The clinical scenarios where it has now been clearly identified and those others where it may also occur and be of clinical importance are also reviewed.