Postoperative results in 21 patients with bone defects that had been treated with a free vascularized fibular graft (FVFG) were evaluated. Pathogeneses in 21 patients were bone defect or pseudarthrosis after trauma in eight, massive bone defect after resection of bone and soft tissue tumor in six, congenital pseudarthrosis of the tibia in six, and congenital arteriovenous fistula in the forearm in one patient. The follow-up ranged from 15 months to 12 years, with an average of four years and six months. At final review, 12 patients went on to primary bony union, and six additional patients obtained union following an additional conventional bone graft. Three FVFGs resulted in a non-vascularized fibular graft. However, two patients obtained union with additional bone graft. Only one patient failed to obtain bony union and eventually required an above-knee amputation. Bony union rates in congenital pseudarthrosis of the tibia treated with the FVFG were lower than those in other diseases. Variables related to the surgical procedures and other factors affecting results and complications were also evaluated.