In 100 patients (75 men and 25 women, mean age 53 years) who had "ad hoc" percutaneous transluminal coronary angioplasty (PTCA) on one or two vessels retrospectively the ECG records were evaluated (signs of necrosis or ischaemia) at rest and/or after exercise and compared with the finding of major obstruction (complete occlusion, stenosis > 50%) on coronarography. In obstruction of the ramus interventricularis anterior the positive ECG finding was consistent with the area of the impaired blood supply in 87%, in case of obstruction of the right coronary artery in 79%, in obstruction of the ramus circumflexus in 90%. In concurrent obstruction of two coronaries despite a 100% positive ECG no close topical correlation was found between coronarography and ECG. On the whole no reliable consistency was found between ECG and kinetic disorders detected by echocardiography. The results indicate that topical analysis of ECG ischaemic findings in patients with coronary arterial disease before planned coronarography contributes to the decision to make "ad hoc" PTCA in affections of one artery. In affections of two arteries ECG is of no particular value.