The hibernating myocardium refers to the presence of persistent myocardial and left ventricular dysfunction at rest, due to reduced coronary blood flow. This left ventricular dysfunction represents an endogenous adaptive mechanism which prevents irreversible cell damage. The dysfunction in hibernating myocardium improves following restoration of coronary blood flow. A key concept in hibernating myocardium is that the reduction in contractile function induced by ischaemia has a protective effect. By reducing oxygen demand the myocardium maintains its viability in the setting of limited oxygen supply. The hibernating myocardium is a new metabolic state that is a consequence of an ischaemic condition, but the hibernating cardiomyocytes are not necessarily ischaemic. There are no adequate animal models for chronic hibernation. However, there are models for acute hibernation both in intact beating hearts and in isolated hearts. In these models a stable reduction in mechanical function for some hours has been demonstrated, whereas metabolic indicators of ischaemia improve during sustained low-flow ischaemia.