Twenty patients with post-menopausal osteoporosis were randomly divided into two groups of ten patients and treated under double-blind conditions with ipriflavone (Osteofix) or placebo. The dosage was 600 mg/day given in three doses and treatment lasted 6 months. All the patients received an oral calcium supply (1 g per day). At baseline and then after 3 and 6 months, the following parameters were controlled: bone mineral content at the lumbar spine, distal radius and femoral shaft; parameters of bone metabolism (alkaline phosphatase, PTH, osteocalcin, calcitonin, calciuria and hydroxyprolinuria); clinical conditions (pain at rest and on movement, motility). Ipriflavone facilitated the conservation of bone mass, that increased in one of the tested areas (distal radius). On the contrary, a bone mineral loss was found in the group treated with placebo, which was significant in the spine. Pain and motility significantly improved in the group treated with ipriflavone; there was an initial improvement in the control group, followed by a sharp worsening. The parameters investigated showed a significant reduction of osteocalcin in the ipriflavone group that indicates a modulation on bone turnover. The drug was well tolerated and compliance to oral treatment was excellent.