Reduction of estrogen levels may underlie the high incidence of 'Tako-tsubo (Ampulla) cardiomyopathy in postmenopausal females. Ovariectomized (OVX) and estradiol-supplemented ovariectomized female rats (OVX + E) were subjected to immobilization stress, an animal model of Tako-tsubo cardiomyopathy. In order to evaluate cardiac changes, left ventriculography and electrocardiography were performed under anesthesia (control). Next day, the conscious rats were exposed to immobilization stress, and left ventriculography was performed (stress). In OVX rats, percentage contraction in left ventriculography was significantly reduced in response to stress, while it was not significantly changed in OVX + E rats. In both groups, heart rate was significantly increased in response to stress. However, heart rate in stress was significantly higher in OVX than in OVX + E rats. In summary, these data suggest that increase of serum estradiol levels can diminish the pathological changes in the heart induced by emotional stress.