Bioimplants containing bone morphogenetic proteins (BMP) such as demineralized bone matrix (DBM) are used clinically to repair bone defects because of their ability to stimulate bone regeneration. Because of handling issues, DBM granules are often combined with an inert carrier, which reduces the DBM content to 40% or less by volume. Recently, Accell DBM100 (Accell, IsoTis OrthoBiologics, Irvine, CA) has been developed, which uses processed DBM as the carrier, resulting in a DBM content of 100%. The purpose of this investigation was to evaluate the use of Accell for bone defect healing.Forty-two athymic male rats were divided into three groups. Bilateral 5 mm calvarial defects were created in each animal. In group 1, one defect was filled with Accell and the other defect was left unfilled (control). In group 2, one defect was filled with OP-1 putty (recombinant human BMP-7 and type I collagen), and the other was left unfilled. In group 3, one defect was filled with Accell and the other with OP-1. Animals were sacrificed at 4 and 8 weeks, postoperatively. Specimens were analyzed by histomorphometry to evaluate bone regeneration quantitatively. Accell and OP-1 both induced significantly more bone at 4 and 8 weeks compared with the unfilled contralateral defects. OP-1-filled defects produced significantly more total reparative tissue (bone + marrow) compared with Accell (P < 0.01); however, the increase in new bone did not reach significance at either time (P = 0.06 at 4 wk; P = 0.10 at 8 wk). In conclusion, these results suggest that Accell DBM100 will be useful in repairing craniofacial bone defects clinically.