This study was performed to evaluate the effects of platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) on the characteristics of beagle dogs periodontal ligament (BPD) cells and bone marrow (BBM) cells which have the important role on the early stage of periodontal tissue regeneration in vitro. In control group, the cells (1.5 X 10 cells/ml) were cultured alone with Dulbecco's Modified Eagle's Medium contained with 109o fetal bovine serum, 50pg/ml ascorbic acid, and 10mM/ml p-glycerophosphate. In experimental groups, growth factors, PDGF or EGF (10ng/ml), were added into the above culture condition. And then each group was characterized by examining the cell proliferation rate, amount of total protein synthesis, alkaline phosphatase activity at 1, 5, 9, 13, 17th day after seeding of cells into the culture wells. The results were as follows ; 1. Both BPD and BBM cells in PDGF-treated group proliferated more rapidly than non-treated cells. This finding also was observed in EGF-treated group but it was not as prominent as that of PD('F-treated group. The proliferation rates of both cells showed the time-dependent pattern during experimental periods in all three groups. 2. Amount of total protein synthesis was more increased in PDGF-treated group than in control group. But no significant difference between EGF-treated group and control group was observed throughout experimental periods even though the tendency of amount of protein synthesis was time- dependent pattern. 3. Alkaline phosphatase activity also more increased in PDGF-treated group than control group. But slight decrease tendency was seen in both cells of EGF-treated group. From the above results, PDGF appeared to enhance the proliferation and cellular activities including amount of total protein synthesis and alkaline phosphatase activity of BPD and BBM cell, but EGF did not show notable effects. The optimal application of these growth factors was thought to be useful as the adjunctive means in periodontal regeneration procedures.