The myocardial contractility function was studied with the aid of echocardiography in 42 male patients during dosaged physical exercises. The patients were selected so that at the peak of the exercises they developed an angina pectoris attack documented by ischaemic ECG changes. In some of the patients the changes were also observed during attacks of angina decubitus. Anginal attacks are accompanied by a reduction of the myocardial function. Haemodynamic reactions of two types were noted with myocardial ischaemia: type I reaction was observed in patients with ischaemic heart disease and practically normal values of the initial heart volume, and consisted in an increasing end-systolic and end-diastolic volumes, with the stroke volume remaining unchanged, and the ejection fraction somewhat decreasing; type 2 reaction was observed in patients with initially increased heart volumes, and consisted in a decreasing end-diastolic and stroke volumes, with an insignificant alteration of the end-systolic volume. The ejection fraction, being initially insignificantly decreased, tends to decrease further during the attack.