To assess the effects of various postmenopausal estrogen replacement therapies on selected cardiovascular risk factors, including high density lipoprotein cholesterol, systolic blood pressure, fibrinogen, and insulin and on osteoporosis risk factors. Conducted in collaboration with the National Institute of Child Health and Human Development, the National Institute of Arthritis and Musculoskeletal and Skin Diseases, The National Institute of Diabetes and Digestive and Kidney Diseases, and the National Institute on Aging. The extended follow-up is for 3 years focusing on endometrium and breast evaluation.