The osteogenic capacity of vascularised periosteum was investigated in rabbits using island rib periosteum nourished by intercostal vessels as an experimental model. Twenty-three adult white female rabbits were used. Excellent bone formation was observed after 2 postoperative weeks in each case. In the early stages of bone formation, extensive chondral ossification was observed. Newly formed bone became mature after 4 to 8 postoperative weeks, on histological examination.