Considerable focus has been directed towards coronary arterial disease in the management of coronary heart disease, however the coronary microcirculation plays a major role in the regulation of coronary blood flow. Thus while we have multiple medical and revascularisation therapies to treat large vessel coronary artery disease, therapies directed towards the microcirculation are very limited. This review paper summarises important aspects of coronary microvascular dysfunction including (a) methods of assessment, (b) clinical classification of associated disorders, (c) possible pathophysiological mechanisms, and (d) potential therapies. Hence this will provide important background to advancing our understanding and management of coronary heart disease by targeting the coronary microcirculation.