OBJECTIVE: To observe the effects of Icariin on ovariectomized osteoporotic rats. METHODS: Female Wistar rats were ovariectomized and administered different dosage of Icariin and 17beta-estradiol for eight weeks. Bone mineral density (BMD), indexes of biomechanics and bone metabolism-associated biochemical markers were measured. RESULTS: Icariin increased the BMD, maximum load and flexural rigidity in the osteoporotic rats. The activities of serum tartrate-resistant acid phosphatase (TRACP) and bone alkaline phosphatase (BALP) were decreased in the Icraiin-fed ovariectomized rats. CONCLUSION: Icariin 225mg/kg per day could increase the BMD and improve indexes of bone biomechanics in ovariectomized osteoporotic rats. It was effective in preventing bone loss induced by ovariectomy.