Ipriflavone (chemical structure: 7-isopropoxyisoflavone), derived from the soy isoflavone, daidzein, holds great promise for osteoporosis prevention and treatment. Ipriflavone (IP) was discovered in the 1930s but has only recently begun to be embraced by the medical community in this country. Over 150 studies on safety and effectiveness, both animal and human, have been conducted in Italy, Hungary, and Japan. As of 1997, 2,769 patients had been treated a total of 3,132 patient years. Preliminary studies have pointed to its effectiveness in the treatment of other conditions involving bone pathology, including Paget’s disease, hyperparathyroidism, renal osteodystrophy, and tinnitus due to otosclerosis. Ipriflavone appears to have several mechanisms of action, all of which enhance bone density, making them seemingly superior to many of the other treatments available for osteoporosis prevention and treatment. IP also inhibits osteoclastic activity (motility and resorptive activity) by modulating intracellular free calcium. IP’s bone-forming mechanisms include stimulation of cell proliferation and maturation of osteoblasts by inhibiting calcium influx into osteoblasts and phosphoinositide hydrolysis. Despite similarities to estrogen, IP possesses no intrinsic estrogenic activity, but does potentiate estrogen. Importantly, IP does not change bone mineral composition or crystalline structure. A clinical trial reported in 2001 that it was not effective in prevention or treatment of osteoporosis.