Beta-tricalcium phosphate (beta-TCP) was grafted into rat mandibular bone defects to assess its potential as a scaffold material for bone regeneration. For this purpose, beta-TCP (TCP), allogenic bone (Allograft), and allogenic bone combined with beta-TCP (Combined) were employed as graft materials. To the left side of the graft materials in the bone defects, platelet-rich plasma (PRP) was added. The rats were sacrificed at one, three, and five weeks. Bone formation rate (BFR), remaining beta-TCP rate (RTR), beta-TCP absorption rate (TAR), whole amount of beta-TCP (WTCP), and total rate of BFR and RTR (TBR) were measured. Combined showed equivalent BFR to Allograft at five weeks, and showed higher RTR at one week and higher BFR at five weeks than TCP. Combined with PRP showed higher TAR than that without PRP at three weeks. Therefore, combination with allogenic bone showed reduced beta-TCP absorption, hence enhancing the role of beta-TCP in bone regeneration. These findings suggested that beta-TCP is a better scaffold for bone regeneration if its early absorption is reduced when used in combination with an osteogenic material.