Objective: To study the effect of Epimedium grandiflorum Morr (EG) on the prevention and treatment of bone loss of the mandible and femur in ovariectomised rats. Methods: A total of 114 adult female Sprague-Dawley (SD) rats were ovariectomised. The effects of EG and oestradiol (ES) on prevention and treatment of bone loss were evaluated. For prevention, both drugs were given the day after ovariectomy. For treatment, the drugs were given 3 months after ovariectomy, when the animal model of osteoporosis was established. The bone density was determined with a densitometer. Newly synthesised collagen was fluorescently labelled with procion red. Results: Three months after ovariectomy, the bone densities of the rat femurs and mandibles were markedly lower than those of the controls, indicating that osteoporosis was successfully established. Administration of EG and ES equally prevented osteoporosis of mandible and femur of ovariectomised rats, and to some extent increased bone density of osteoporosis rats. Conclusion: EG was effective in the prevention of osteoporosis of the mandibles and femurs. EG was also somewhat effective in the treatment of osteoporosis of femurs. Keywords: Chinese herbal medicine, Epimedium grandiflorum Morr, mandible bone loss, osteoporosis