Raloxifene (Evista) is a prescription drug that is used to prevent and treat osteoporosis. It is chemically related to another drug called tamoxifen (Nolvadex), a common treatment for breast cancer. Unfortunately, tamoxifen causes many unwanted side effects, so alternative therapies are desirable. The National Cancer Institute recently released the first results of a clinical trial that evaluated the differences in raloxifene and tamoxifen in preventing breast cancer. Postmenopausal women were given 60 mg of raloxifene or 20 mg of tamoxifen and followed for 5 years. Both drugs decreased the risk of developing invasive breast cancer by 50%. Women in both groups had equivalent numbers of strokes, heart attacks, and fractures, but those who took raloxifene had fewer side effects. Women who are taking tamoxifen and have not experienced problems are not being encouraged to switch to raloxifen. If approved by the FDA, raloxifene may become an important alternative for the prevention of invasive breast cancers in women who may not be able to tolerate tamoxifen.