The current study seeks to capitalize on the knowledge gleaned about PTH-induced stimulation of bone formation prior to resorption in subjects on antiresorptive therapy such as estrogen or alendronate. In this protocol we have chosen to give PTH by daily subcutaneous injection in the presence of alendronate. We have already shown that with 6 weeks of daily subcutaneous h(1-34)PTH 400 U/day in patients on established alendronate, biochemical indicators of bone formation are substantially increased (30-60 percent), with no stimulation of resorption over this time frame.