In a group of patients with chronic ischaemic heart disease whose diagnoses were ascertained by the clinic, by the electrocardiogram after resting and after work, by the coronarography and/or by the complication of the ischaemic heart disease (myocardial infarction), we compared the findings of the classical ECG with those ones of the ST-mapping. In 32% the ST-mapping brought an increased evidence. A correspondence of 100% we found in the certainly normal and certainly pathological findings. The maxima of the repolarisation disturbances withdrew from the proof of the Wilson derivations at rest at 54.8% and under submaximal strain at 79.3%, changed in 25.8% their position under load and during the load the emigrated in 16.5% out of the precordial leads after Wilson. The evaluated sums of the partial surfaces of the ST-mapping have a higher correlation to the severity of the ischaemic heart disease, permit a better differentiation between the individual degress of severity and render possible an exacter judgment of the prephase of the ischaemic heart disease than it is possible with the usual ECG. In 25.8% of all examinations after work repolarisation disturbances limited to small myocardiac areas could be proved only by means of the mapping. The localisation of lesions of the myocardium is better possible by means of the ST-mapping above all dorsally/caudally than by means of the classical ECG.