OBJECTIVE This study was designed to examine whether short-term estrogen administration ameliorates dobutamine-induced myocardial ischemia in postmenopausal women with coronary artery disease (CAD). BACKGROUND Estrogen replacement therapy in postmenopausal women is associated with a marked reduction in the risk of CAD. Estrogen has been reported to have both short- and long-term effects on the cardiovascular system. However, it remains to be examined whether short-term estrogen administration ameliorates myocardial ischemia caused by increased myocardial oxygen demand in postmenopausal women with CAD. METHODS Eight postmenopausal women with proved CAD underwent dobutamine stress echocardiography (DSE). DSE was performed three times in a placebo-controlled, double-blind manner: 1) 30 min after intravenous administration of saline solution (placebo) and after 2) a low dose (1.25 mg) and 3) a high dose (10 mg) of conjugated estrogen. The effects of estrogen were compared at the maximal comparable stage of DSE, which was the maximal DSE level that the same patient achieved in all three examinations. RESULTS Estrogen dose-dependently ameliorated the dobutamine-induced worsening of symptoms (prolonging time to onset of symptoms by 52% [low dose] and 72% [high dose]), electrocardiographic findings (decreasing the magnitude of summed ST segment changes by 36% [low dose] and 76% [high dose]) and left ventricular wall motion (reducing the wall motion score index by 50% [low dose] and 77% [high dose], all p < 0.01 by analysis of variance). There was no significant difference in blood pressure, heart rate or rate-pressure product among the three examinations at the maximal comparable stage of DSE. CONCLUSIONS Estrogen has short-term anti-ischemic effects on the myocardial ischemia induced by increased myocardial oxygen demand in postmenopausal women with CAD.