Findings in animals and humans with sclerostin deficiency as well as results of preclinical and early clinical studies with sclerostin inhibitors demonstrated a new treatment paradigm with a bone building agent for the management of patients with osteoporosis, the antifracture efficacy, and long-term tolerability of which remain to be established in on-going phase III clinical studies. The gene discussed is SOST; the disease is osteoporosis.