Daily subcutaneous injection of a synthetic human parathyroid hormone fragment, combined with daily ingestion of 1,25(OH)2 vitamin D, significantly increased trabecular bone density in the spine (p less than .01), and improved intestinal calcium and phosphorus absorption and total body retention of dietary calcium and phosphorus in middle-aged men with idiopathic osteoporosis. The increases in spinal bone mineral were marked and progressive during a year of treatment. These results indicate that increasing intestinal absorption of dietary calcium while simultaneously stimulating new bone formation with small doses of parathyroid hormone can restore spinal bone in osteoporotic men.