Since 1979, nine children had been treated by free fibular graft in our hospital. Five of them were males, and 4 were females, with a mean age of eight years. The average length of the skeletal defects was 7 cm. The average length of the fibula that was removed for reconstruction was 12.3 cm. The blood circulation of the donor bone was re-established by direct anastomosis of one peroneal artery and vein of the transfer with the appropriate artery and vein of the host region. Nine patients had been followed from 1 year to 9 years,avereged 5.5 years. S even grafts which were substituted in the tibia defects took the same shape and caliber as that of the normal tibia with canalization of the marrow cavity . From the roentgenographic examination of the side where the fibular graft was removed, there was definite caudal migration of the upper fibular in 5 cases,averged 5.2mm,while in 7 cases there was cephalic migration of the distal fibular segments,averaged 4.3mm. The breadth of ankle mortise where increased in 7 cases,The tibio-talus angle was averaged 7 degrees,in 3 cases. In 3 of the 9 cases during follow-up,alaterl wedging of the distal tibia epiphysis with lateral tilting of the talus invarably associated with instability of the ankle was evident. We believed that the elevation of the lateral malleolus and latral wedging of the distal tibia epiphysis were responsible for instability of the ankle.