Both tibolone and raloxifene have been demonstrated to prevent postmenopausal bone loss. During treatment with tibolone bone mineral density (BMD) of the spine has been shown to be increased between 1.8 and 5.8 % above baseline in two years, depending on the population studied. Since treatments aimed at prevention should ideally be used long-term, compliance with the treatment is crucial. Efficacy of and compliance with the two treatments will be measured and evaluated.

Inclusion Criteria:

• Only subjects who give voluntary written informed consent, and who are willing and able to make reasonable efforts to observe all clinical trial requirements are to be enrolled.

• Subjects will be osteopenic but otherwise healthy postmenopausal women, from 60 to 79 years of age (inclusive) at entry.

• Screening BMD of the lumbar vertebrae (L1-L4) must be between -2.5 SD and

  • 1.0 SD of the T-score.

• Subjects should have a Body Mass Index (BMI) >19 and < 30 kg/m2.

Exclusion Criteria:

• Spinal X -ray with symptomatic vertebral fracture (more than 20% reduction in expected vertebral height).
• History of bilateral hip replacements.
• Subjects who are not ambulatory.
• History or presence of any malignancy, except non-melanoma skin cancers.
• TVUS double wall thickness > 4 mm, or any other undiagnosed abnormalities visualized by TVUS.
• Abnormal cervical Pap smear result
• Undiagnosed abnormal (in the investigator's opinion) vaginal bleeding in the past year prior to screening.
• Mammography or physical examination finding that is suspicious of malignancy.
• Uncontrolled hypertension
• Bone disease other than osteoporosis such as Paget's disease, osteomalacia or bone metastases.
• Drinking more than 4 glasses of alcohol containing drinks per day.
• Smoking more than 20 cigarettes a day.
• Current or recent prolonged use of hepatic microsomal enzyme-inducing anticonvulsant medication or other drugs known to interfere with or otherwise alter the pharmacokinetics of steroids.
• Treatment with anabolic steroids, calcitonin or raloxifene within the last 6 months.
• Treatment with alendronate and risedronate more than 6 months. If treatment duration was less than 6 months a wash-out period of 12 months is necessary.
• Treatment with etidronate for 1 year a wash-out period of 6 months is necessary. If treatment period of more than 1 year a wash -out period of 12 months is necessary.
• Treatment with oral estrogen and/or progestin therapy (including contraceptives) or transdermal therapy and local estrogen applications within 6 months prior to screening/baseline BMD measurements (i.e. the wash -out period of 6 months must have been completed before the screening / baseline BMD assessments are made). A 20-week wash-out for injections of MPA-containing contraceptives (e.g. Depo-Provera®) is required.
• Ever use of estrogen and/or progestin containing implants.
• The use of cholesterol-lowering medicine cholestyramine or colestipol.
• Subjects with a change in thyroid medication within the last 6 weeks prior to screening.
• Subjects who have had fluoride treatment for 2 weeks or more (> 2 mg/day fluorideion) at any time (NaF tablets for caries prevention is allowed).
• Subjects who have undergone systemic glucocorticoid treatment (> 5 mg prednisone or equivalent/day) for more than one month within the past 6 months (prior to BMD screening assessments).
• Subjects who are receiving or require medication for the treatment of osteoporosis except Calcium / Vit D.
• The use of coumarin products.
• Type I diabetes mellitus.
• Presence or history of thromboembolic disorders.
• Serious decompensated renal or liver disease.
• Abnormal laboratory values
• Any condition or disease that could result in altered absorption, excessive accumulation, impaired metabolism, or altered excretion of the investigational product.