 The primary goal of this randomized, controlled trial is to determine if ERT stabilizes, retards, andor reverses the progression of atherosclerosis in postmenopausal women. We will further evaluate the association of lipid and non-lipid factors of ERT-mediated reduction in the progression of early atherosclerosis. Ultrasonography will be used to measure the rate of change in the thickness of the carotid artery. Blood samples will be used for measuring lipid and non-lipid mediators of ERT. 