Recent studies on the fate of pedicle osteocutaneous grafts have shown that they remain viable and may be actively involved in the mechanics of bone repair. This communication reports on a series of experiments aimed to clarify the role of periosteum in the survival of pedicle-assisted bone grafts. Osteocutaneous grafts were developed in dogs in such a manner as to isolate the implant from normal recipient bone. Free bone grafts were used as controls and a group of pedicle periosteal grafts were studied as potential sources of bone formation. Specimens were evaluated at regular intervals over a 40-week period. The pedicle bone grafts maintained their viability and developed vigorous osteoneogenesis. The process was progressive and eventually resulted in partial substitution of the original graft by new bone of periosteal origin. The free bone grafts were resorbed and no bone formation was obtained in pedicle periosteum specimens. The study provides clear evidence that under experimental conditions no bone contact is needed to maintain the viability of pedicle osteocutaneous grafts. It also shows that the periosteum has the leading role in the restructuring process of these grafts.