Women who self-select to take postmenopausal hormones have lower risks of coronary heart disease, their leading cause of mortality. Women and their primary health care providers must weigh this and other clear (osteoporosis), and possible (stroke, colon cancer, and Alzheimer's disease) benefits against clear (endometrial cancer) and possible (breast cancer) risks. Because all existing data derive only from observational studies, reliable information on the balance of risks and benefits must await the results of the Women's Health Initiative, a large-scale, randomized clinical trial.