The authors analyse 52 results of false-negative bicycle ergometry tests in patients with ischemic heart disease and stenosing coronary atherosclerosis (according to the findings of coronarography). During bicycle ergometry all patients attained submaximum pulse rate (85% of the maximum) and had a high tolerance (808 kgm/min, on the average) to exercise. False-negative results were encountered most frequently in isolated lesion of one of the coronary arteries (usually the left anterior descending branch). The frequency of myocardial ischemia detection during bicycle ergometry did not depend on the presence or absence of collaterals.