The finding of transient ST-segment depression during episodes of supraventricular tachycardia is common but its ischemic significance is usually uncertain. Several authors came to the conclusion that in the absence of positive myocardial scintigraphy these alterations are not associated with a coronary flow-limiting stenosis. Our report tends to confirm this view but we suggest to observe the evolution of ST-segment changes at the very end of the episodes; these mechanisms have not been adequately addressed in previous studies and could provide useful clues to the ischemic or non-ischemic origin of ST-segment abnormalities.