This trial found that 1-34 human parathyroid hormone (hPTH [1-34]) significantly increased bone mass in postmenopausal women with osteoporosis receiving hormone replacement therapy and increased osteocalcin levels by more than 55% early in the course of its use, supporting its status as a medication with a significant osteogenic effect that reduces the risk of vertebral fracture, and suggesting its potential use in the treatment of postmenopausal osteoporosis. The gene discussed is PTH; the disease is osteoporosis.