• An open-label treatment phase will extend the study for 1 year beyond the primary endpoint. During this final year of the study all patients will receive raloxifene.
• The purpose of lengthening is to assess the differences in response to raloxifene when it is administered immediately following versus 1 year after(with and without a washout period) withdrawal from teriparatide.

The purpose of this study is to determine whether the increase in spine bone mineral density that has been generally observed in previous clinical studies involving the study drug can be maintained or even increased if followed with raloxifene HCl. All qualifying study participants will receive the study drug followed by treatment with raloxifene HCl or placebo. All study participants will receive raloxifene HCl in the third phase of the study.

• Drug: teriparatide
• Drug: raloxifene HCl
• Drug: placebo

Inclusion Criteria:

• Must be diagnosed with osteoporosis
• Must be female, age 55 through 80
• Must be at least 5 years postmenopausal
• Must be free of other severe or chronically disabling conditions
• Must be able to properly use injection device.

Exclusion Criteria:

• Must not have bone diseases other than osteoporosis
• Must not have history of certain cancers
• Must not have certain medical diseases (inflammatory bowel disease, malabsorption syndrome, kidney or bladder stones, venous thrombi or emboli, recent vaginal bleeding due to unknown causes)
• Must not have treatment with particular medications (warfarin, estrogens, androgens, steroids, calcitonins, fluorides, biphosphonates)
• Must not have known allergy to the study agent or raloxifene HCl