Objective: The Purpose of the study was to investigate the bone morphogenic protein expression of rhBMP-2(recombinant human bone morphogenic protein-2) as singnaling molecule and ${eta}-TCP$(Tricalcium phosphate) as a bone substitute and carrier medium of rhBMP-2. Materials and Methods: 16 rabbits divided into 2 group of each 8 rabbit. Two standardized bone defect, round bilateral defect was made in the cranium of the 8 rabbit of first group, and was grafted with $150{sim}500{mu}m$ diameter ${eta}-TCP$ 0.25g in one side, which was soaked with rhBMP-2, and autogenous bone was grafted on another side as a positive control. Second group of 8 rabbit, only ${eta}-TCP$ was grafted with same size and same manner. After 2, 4, 8, and 12 weeks, specimen was taken for microscopic immunohiostochemical and histomorphometric analysis. Result: Grafting ${eta}-TCP$ with rhBMP show the early formation of the bone regenerative factor (BMP-4) and more quantity of new bone formation than only use of ${eta}-TCP$ (8,12 week), even show less new bone formation than autogenous bone. Conclusion : The experimental study result that ${eta}-TCP$ graft combination with rhBMP-2 as a delivery system is an effective with osteoinductive capacity and biodegradable properties, so that provide clinical availibility of composite use in reconstruction of bony defect.