Lifetime risk is a useful way to estimate and compare the risk of various conditions. Hip fractures, Colles' fractures, and coronary heart disease, and breast and endometrial cancers are important conditions in postmenopausal women that might be influenced by the use of hormone replacement therapy. We used population-based data to estimate a woman's lifetime risk of suffering a hip, Colles', or vertebral fracture and her risk of dying of coronary heart disease. A 50-year-old white woman has a 16% risk of suffering a hip fracture, a 15% risk of suffering a Colles' fracture, and a 32% risk of suffering a vertebral fracture during her remaining lifetime. These risks exceed her risk of developing breast or endometrial cancer. She has a 31% risk of dying of coronary heart disease, which is about 10 times greater than her risk of dying of hip fractures or breast cancer. These lifetime risks provide a useful description of the comparative risks of conditions that might be influenced by postmenopausal hormone therapy.