Coronary insufficiency is defined. Some specialities of coronary circulation and aspects of their regulation are discussed. Physical mechanisms such as arteriovenous pressure gradient, vascular and extravascular components of the coronary resistance, the influence of rhythm change on the contraction-conditions of the myocardium, as well as the pulse-rate are differentiated from biological regulation mechanism, such as metabolic, nervous and hormone influences. The typical distrubance of this regulation in the coronary insufficiency is emphasized including impaired left ventricular function. In the second part, the clinic or coronary insufficiency deducted from the anatomical-pathological lesions as well as their pathophysical relations is dealt with, for instance manifestation of angina pectoris and myocardial infarct. The indications and contra-indications for selective coronary angiography are described.