The purpose of this study is to evaluate the effect of alfacalcidol 1 µg daily on the number of fallers in postmenopausal, alendronate-treated, osteopenic or osteoporotic women.

primary outcome = number of fallers (patients with at least one locomotor fall incl.mixed falls)

Inclusion Criteria:

• age > 65 years
• postmenopausal women
• osteopenia/osteoporosis as defined by WHO criteria

Exclusion Criteria:

• Neoplasm or other severe diseases with life expectancy less than one year or expectation of rapid worsening within one year
• Chronic inflammatory rheumatoid disease
• Arthritis with continuous pain and influence on locomotion
• Inflammatory or metabolic bone disease, excluding osteoporosis.
• Subjects with antiosteoporotic medications who are not willing to switch over to alendronate treatment. Estrogen treatment can be continued
• 25-OH-Vitamin D3 < 12 ng/ml (12 ng/ml = 30 mmol/L)
• Systemic corticosteroid treatments of more than one month within previous 12 months
• Intolerability for alfacalcidol
• Hypercalcaemia (>2,7 mmol/l)
• Milk alkali syndrome
• Uncorrected, severe visual impairments
• Creatinin > 2.5 mg/dl (>220 µmol/L)