A critical study of the electrical criteria for coronary insufficiency was undertaken on the basis of a group of 150 patients who underwent a selective coronary arteriography and a submaximal effort electrocardiogram and free of any functional coronary insufficiency. The three following notions became apparent: -- a downward displacement of the J point is greater than or equal to 4 mm has a very high predicitive value (90%) for coronary insufficiency, whatever the slope of the following ST segment; -- anslowly ascending, rigid ST segment with a slope included between 0.1 and 1 mV/sec. has a value equivalent to that of the classical criterion: horizontal or descending slope of the ST segment greater or equal than 1 mm; -- the ischaemic index put formard by McHenry (J is less than or equal 1 - J + ST is greater than or equal 0) is not specific enough to be of practical value.