The bony repair effect of different Calcium Phosphate Bone Cements was tested in a dog model. Seven different formulations were synthesized and tested on their biocompatibility, osseoconduction and biodegradability. Three dogs were used in this pilot study, in each dog 4 cranial, circular defects were made with a critical size diameter of 12 mm. Autologous bone was used as a control. The dogs were sacrificed after 6 months. Mineral phase analysis showed a reaction of the cements to form a more or less crystalline calciumhydroxyapatite. Histologic evaluation revealed that the presence of the cements stimulated the formation of a thin bone layer on the cranial and caudal side of each defect. The cements did not evoke an inflammatory reaction. Two formulations showed extensive bone formation. (C) 2003 Kluwer Academic Publishers.