Objectives : The author aimed to evaluate the effect of BuOH fraction(ST) from Schizonepeta tenuifolia on osteoblast proliferation in murine calvarial cells. Methods : The osteoblast separated from murine calvariae was cultivated for 10 days and evaluated the cell function. After the addition of ST on the culture medium, we determined the effect of ST on the cell proliferation, protein synthesis, alkaline phosphatase activity, collagen synthesis, and apoptosis of the osteoblast. Results : 1. ST increased the proliferation of osteoblast, and restored the decreased cell number in glucocorticoid (GC)-treated osteoblast. 2. ST increased protein synthesis of osteoblast, and restored the decreased protein synthesis in GC-treated osteoblast. 3. ST increased ALP activity of osteoblast, and restored the decreased enzyme activity in GC-treated osteoblast. 4. ST increased collagen synthesis of osteoblast, and restored the decreased collagen synthesis in GC-treated osteoblast. 5. ST did not change the survival rate of osteoblast, but increased the survival rate in GC-treated osteoblast. Conclusions : It is concluded that ST might reduce the osteoporosis resulted from augumentation of osteoblast proliferation.