Objectives : This study was undertaken to study the action mechanism of Rhizoma Davalliae (RD) at parameter related to regulating bone density. Methods : We measured alkaline phosphatase activity and the contents : calcium, hydroxyproline, osteocalcin, calcitonin, and parathyroid hormone after the ovariectomized rats had been treated with RD for 30 days. Results : The following changes occurred: First, the serum calcium content and the calcitonin content, which decreased in ovariectomized rats, increased with RD treatment. Second, the serum alkaline phosphatase activity, the parathyroid hormone ativity, the osteocalcin content, the urinary calcium content, and the hydroxyprolin content-which increased in ovariectomized rats-decreased with RD treatment. Conclusions : These results show that RD treatment can recover abnormal calcium metabolic process by sex hormone inequality, promoting bone formation and inhibiting bone absorption.