Earlier work suggested that Ginseng saponin had an effect on healing of fracture and osteoporosis, hut there has heen no report on saponin effects on cultured osteoblast. The purpose of this study was to investigate the effect of saponin on cultured osteovlast of the mouse. Osteohlastic cells were isolated from periosteum-stripped parietal bones of neonatal rat calvaria, seeded at 4 x 10 4 cells/cm2 density, and cultured in standard medium and deficient medium, with addition of saponin (0(control), 10, 20, 50 microgram/ml concentration). Plating efficiency(adhesiveness), proliferation and the alkaline phosphatase activity of the osteohlasts were evaluated on 2 hours, days 2 and 7 of culture. Saponin was found to enhance the adhesiveness of seeded osteoblasts which were cultured with a deficient medium in comparison to the controls. It promoted cell proliferation of the osteoblasts cultured with a deficient medium in comparison to the controls. There was also a significantly enhanced increase of alkaline phosphatase levels in the presence of saponin during culture with deficient medium in comparison to the controls. In summary, the results showed that the saponin increased adhesiveness, proliferation and the alkaline phosphatase activity of the osteoblast cultured only in deficient medium.