Ginseng Radix(GR) had been used widely from oriental medicine and the effects of it have been investigated by many researchers. The purpose of present study was to investigate the effects of GR on the cell cycle progression and its molecular mechanism in human fetal osteoblast. The results were as follows. Increased cell proliferation was observed in cells exposed to 100 ng/ml, 10 ng/ml of GR-1 at 12 hours and 24 hours, 1 ${mu}g$/ml of GR-1 at 48 hours, and 100 ${mu}g$/ml, 10 ${mu}g$/ml of GK-2 at 12 hours, all treatment groups of GR-2 at 24 hours(p<0.05). S phase and G1 phase was increased in the group of treated with 100 ng/ml of GR-1, with 10 ${mu}g$/ml and 1 ${mu}g$/ml of GR-2, with 100 ${mu}g$/ ml and 10 ${mu}g$/ml of GR-3 in the cell cycle analysis. The cell cycle regulation protein levels of Cyclin D1, Cyclin E, CDK 2. CDK 4 and CDK 6 were increased in the group of treated with 1 ${mu}g$/ml and 100 ng/ml of GR-1, with 10 ${mu}g$/ml and 1 ${mu}g$/ml of GR-2, with 100 ${mu}g$/ ml and 10 ${mu}g$/ml of GR-3. On the other hand, p21 was decreased in the treatment group with 1 ${mu}g$/ml and 100 ng/ml of GR-1, with 10 ${mu}g$/ml and 1 ${mu}g$/ml of GR-2, 10 ${mu}g$/ml of GR-3, and p53 and p16 was decreased in the treatment group with 100 ng/ml of GR-1, 100 ${mu}g$/ml and GR-3 and pRb was decreased in the all treatment groups except 1 ${mu}g$/ml of GR-1. These results suggested that GR increases the cell proliferation and the cell cycle progression in human fetal osteoblast, which is linked to increased cell cycle regulation protein levels of Cyclin D1 , Cyclin E, CDK 2, CDK 4, CDK 6 and decreased cell cycle regulation protein levels of p21, pRb.