Abstract Objective: To determine the timely ingrowth of new blood vessels of composite endochondral (EC) bone and demineralized bone matrix (DBM) prepared from intramembranous (IM) origin (EC-DBMIM) and to compare it with EC bone graft alone. Design: Thirty-two rabbits with 32 critical-size (10 × 5 mm), full-thickness bony defects in rabbit parietal bone were divided into two groups: composite EC-DBMIM group—implanted with composite autogenous EC bone and DBMIM; EC bone group—implanted with EC bone alone. Two rabbits from each group were sacrificed 1, 2, 3, 4, 5, 6, 7, and 14 days after grafting. Neovascularization was assessed by immunohistochemical staining with antihuman angiogenesis-related endothelial cell antibodies (EN 7/44). Quantitative analysis of neovascularization, represented by percentage area of positive immunohistochemical staining, was performed on 320 sections of the experimental groups by a computer-assisted image analyzer. Results: Positive immunohistochemical staining was first identi...