Using the Korean red ginseng saponin, which is known to world-wide and thd effects of it have been investigated by many reserachers for years. Ginseng saponin, one of the major components of Korea ginseng root, has many various biologic effects, such as cytotoxic effect, tumorcidal activity, protein biosynthesis and membrane modifying effect. The purpose of this study was to evaluate effects of ginseng saponin on the alkaline phosphatase activity of ROS cells in culture. After ROS cells were seeded into a 96-well plate, 96-well plate cultured until confluence was obtained. To evaluate cytotoxic effect of total saponin in cultured ROS cells, the plates were added to each total saponin concentration (0-1mg/ml). After 48hr., cells were counted by stain with 0.2% trypan blue at randomly selected field microscopically. Also, to evaluate alkaline phosphatase(ALP) activity of total saponin in cultured ROS cell, the plate was added to each total saponin concentration (0-1mg/ml) and ALP activity was assayed. To evaluate time-course of ALP activity, $31.25{mu}g/ml$ of saponin added to 96-well plate. After culture of 6, 12, 24 and 48hr., ALP activity test was performed. To evaluate effect of cycloheximide in ALP activity, 96-well plate was added to saponin and cycloheximide. In control group, the plate was added saponin only. The results were as follows. 1. After the various concentration of total saponin was added in the medium, 500 and $1000{mu}g/ml$ of total saponin showed cytotoxic effect of ROS(P<0.005). 2. In contrast to control group, 7.6, 15.6, 31.25, 62.5 and $250{mu}g/ml$ of total saponin increased ALP activity significantly. 3. Otherwise, 500 and $1000{mu}g/ml$ of total saponin decreased ALP activity significantly(P<0.005). 4. As the time span increases, $31.25{mu}g/ml$ of total saponin increased ALP activity. 5. Cycloheximide decreased saponin-indueced ALP actitity in ROS(P<0.005). These results suggest that Ginseng total saponin stimulates the ALP activity of rat osteoblastic cells.