The aim of the present study was to examine the healing of endochondral (EC) autogenous bone grafts in the presence of demineralised bone matrix prepared from intramembranous bone (DBMIM), or prepared from endochondral bone (DBMEC) using quantitative analysis. Thirty bone defects were created on the parietal bone of fifteen New Zealand White rabbits. In the experimental groups, five defects were grafted with EC bone, five defects were grafted with EC bone mixed with DBMIM (EC-DBMIM) and six defects were grafted with EC bone mixed with DBMEC (EC-DBMEC). In the control groups, ten defects were left empty (passive control) and four defects were grafted with rabbit skin collagen (positive control). They were all sacrificed at day fourteen post grafting, and the defects were prepared for histological analysis. Serial sections were cut across the whole defect. Quantitative analysis was performed on 152 sections of the experimental groups by image analysis. Four hundred and fourteen per cent more new bone was formed in defects grafted with composite EC-DBMIM than those grafted with EC bone alone (p < 0.001). Eighty-five per cent more new bone was formed in defects grafted with composite EC-DBMEC than those grafted with EC bone alone (p < 0.001). No bone was formed in either passive or positive controls. In conclusion, DBM, especially DBMIM, have extremely high osteoinductive properties and greatly enhance the integration of EC bone grafts with defects created in IM bone.