The study is for Korean women who are postmenopausal and also suffer from osteoporosis.

The study will test if women who are given 20 mg of arzoxifene once a day for six months have a less severe level of osteoporosis than those women who do not take arzoxifene.

All patients will receive 500 mg of elemental calcium and 400 to 600 IU Vitamin D daily starting 4 weeks prior to study drug administration continuing through the 6 months of therapy.

Inclusion Criteria:

• Present with osteoporosis based on total hip, femoral neck or lumbar spine BMD T-score of less than or equal to -2.5 but must never have had any osteoporotic fragility fracture.
• Are ambulatory and are 60 to 85 years of age, inclusive. Aside from diagnosed osteoporosis (Inclusion Criterion [1]), all women must be free of severe or chronically disabling conditions, have a life expectancy of at least 5 years in the opinion of the investigator, be expected to remain ambulatory throughout the entire study, and be expected to return for follow-up visits.
• Had their last natural menstrual period at least 2 years before beginning the study.
• Are able to comprehend the requirements and procedures for the study and to provide informed consent before entering the study.
• Have at least two lumbar vertebrae (L1 to L4) that are evaluable via dual energy X-ray absorptiometry (DXA) and lateral thoracic and lumbar spine x-ray films that can be adequately evaluated for existing vertebral fractures at screening.
• Have centrally read total hip, femoral neck or lumbar spine T-score less than or equal to -2.5

Exclusion Criteria:

• Have known current metabolic bone disorders other than low bone mass, such as hyperparathyroidism, renal osteodystrophy, or osteomalacia.
• Have known, suspected, or history of carcinoma of the breast or estrogen-dependent neoplasia (e.g., endometrial or uterine carcinoma), except for hysterectomized patients with a history of carcinoma in situ of the uterus. For other cancers, be disease free and in remission from all other cancers for 5 or more years, except for excised superficial lesions, such as basal cell carcinoma or squamous cell carcinoma of the skin.
• Have demonstrated or suspected allergy to raloxifene or arzoxifene
• Have unexplained or abnormal vaginal bleeding within 6 months prior to Visit 1 or between Visit 1 and Visit 2.
• Are experiencing clinically severe postmenopausal symptoms that may require estrogen-replacement therapy.
• Have a history of or suggestion on ultrasound or pelvic examination of a pre-existing gynecologic abnormality that would require further gynecologic treatment (e.g., ovarian cysts, large fibroids, undiagnosed adnexal masses) or of baseline endometrial thickness of >5 mm.
• Have Papanicolaou's tests showing malignant or premalignant findings.
• Have active or any past history of thromboembolic events
• Have active or any past history of atrial fibrillation.
• Have a history of cerebrovascular accident or documented transient ischemic attack at any time in the past.
• Have acute or chronic liver disease defined as alanine aminotransaminase (ALT) >100 U/L, gamma-glutamyl transferase (GGT) >400 U/L, or late stage cirrhosis without transaminase elevations.
• Have impaired kidney function (serum creatinine >177 micromol/L or >2.0 mg/dL).
• Have vitamin D deficiency prior to enrollment (Visit 2; 25-hydroxyvitamin D less than10 ng/mL or less than 24.9 nmol/L).
• Have any known, severe, or untreated malabsorption syndromes.
• Have endocrine disorders requiring pharmacologic therapy except for type II diabetes and hypothyroidism. Patients on a stable dose of thyroid replacement therapy during the 6 months preceding randomization (Visit 2) who are clinically euthyroid in the opinion of the investigator may enroll in the trial.
• Consume an excess of alcohol or abuse drugs
• Represent an unacceptable medical or psychiatric risk for treatment with an investigational drug
• Have active or any history of seizure disorder.