The purposes of this study are to determine:

• The effects of arzoxifene on bone mineral density (bone mass) at the spine and hip in postmenopausal women.
• The effects of arzoxifene on the uterus (womb) in postmenopausal women.
• The effects of arzoxifene on blood tests that measure changes in bone rebuilding in postmenopausal women with low bone density.
• The effects of arzoxifene on blood lipids (fats) and other blood markers of heart disease risk.
• The safety of arzoxifene and any side effects that might be associated with its use.

Inclusion Criteria:

• Female
• 45 to 60 years of age, inclusive
• At least 2 years since last menstrual cycle
• Intact uterus (womb).

Exclusion Criteria:

• Existing fracture of the spine.
• Bone disorders, other than low bone mass
• History of cancer in the last 5 years. Also, any history, at any time, of breast cancer or cancer of the lining of the uterus.
• Abnormal or unexplained vaginal bleeding.