This experimentally designed study was carried out to compare coral and cancellous autograft applications in femoral fractures with large bone defect in 16 dogs of different breed, age, sex and weight.

The dogs were divided equaly into two groups. Segmental defect at the lenght of 1 cm was constituted in femur diaphysis. Segmental defects were filled with natural coral graft in one group and cancellous bone graft in another.

Clinical and radiographical evaluations were performed in the 1^st, 2 ^nd , 3 ^nd and 6^th month. Two dogs in each group were euthanized. Histopathological examination was performed in graft applicated regions.

Operation time in coral implant applications were shorter than those in cancellous graft applications. It was observed that -the coral implant applicated cases generally used their related extremity earlier than the cancellous graft applicated ones.

Progressive resorbtion and new bone formation began in coral implants from the 1st month. Implants resorbtion continued in the course of time but complete resorbtion was not observed in any cases at the end of 6 month period. However, rejection was not observed in any of the cases.

New bone formation which started in the 1^st month increased with time in cancellous bone graft applicated cases. The defects were filled fully and bone unity was obtained at the end of 6 month period.

In conclusion, cancellous autograft is a good graft material. On the other hand, coral implantation does not require a second operation to obtain graft material. The application is economical, easy to obtain and to shape. It does not cause rejection. It is compatible with tissues and can be resorbed. Natural coral implants can be used in insufficient cancellous autograft cases.