Congestive heart failure (CHF) is a leading cause of morbidity, mortality, and hospitalization in women. The increase in mortality suggests that postmenopausal estrogen loss may alter the phenotypic expression of CHF. Because estrogen is a potent in vitro inhibitor of pro-inflammatory cytokines (e.g., TNFa, IL-1B, IL-6), which are re-expressed by the failing myocardium in patients with CHF and are related to an adverse prognosis, the study postulates that estrogen replacement will improve the outcome of postmenopausal women with CHF.