The cells of the cardiovascular system generate and release the compound adenosine in increasing quantities when they are “stressed” or subjected to injury/disease. This increased amount extra-cellular adenosine can then interact with receptors in myocardial, vascular, and inflammatory cells to regulate their function. In addition, the adenosine formed can be rapidly re-incorporated back into the cells ‘nucleotide’ pool to aid in maintenance of energy. Via these receptor-dependent and independent (metabolic) paths adenosine plays a crucial role in controlling the balance between energy supply and demand in the heart, and providing tolerance to damaging conditions such as ‘ischaemia’ (myocardial infarction or heart attack). The molecular basis for control of adenosine release, and the precise actions of adenosine, remain incompletely understood. Amongst other things, our research over the past 16 years has contributed to our knowledge regarding formation and actions of adenosine in the normal and diseased heart. What follows is a lay description of some of this work - a portion of the story of adenosine in the heart.