1. Inlay grafts of calf cortical bone, processed to lower antigenicity, were compared with fresh autogenous cortical bone in dogs one and six months after operation.
2. The incorporation of both types of bone was similar initially and there was no evidence of an inflammatory response with characteristics of the "heterograft reaction" at thirty days.
3. After six months, the heterografts were more completely remodeled than the autografts as judged by gross, radiographic, histological, and microradiographic criteria.
4. These preliminary studies indicate that this material may be a substitute for preserved bone homografts.