This study assessed the acute effect of intravenous conjugated equine estrogen on metabolic coronary vasodilation to atrial pacing in 22 postmenopausal women with coronary disease or risk factors for atherosclerosis. Impaired metabolic coronary vasodilation is present in postmenopausal women with atherosclerosis or its risk factors and is not acutely augmented by the intravenous administration of Premarin.