In general, epidemiologic data from case-control and cohort studies have suggested that postmenopausal estrogen use confers a moderate degree of protection from coronary artery disease. The authors report reductions in all-cause mortality rates and in mortality rates for acute myocardial infarction among estrogen replacement users in comparison with never-users. It is calculated that even a small decline in the mortality rate for coronary artery disease among estrogen users would have a major impact on the overall risk/benefit ratio associated with estrogen use.