Four patients with neurofibromatosis and a dysplastic type of congenital pseudarthrosis of the tibia were treated by resection of the lesion and reconstruction of the extremity with a free vascularized fibular graft. Solid union of the graft was achieved within 3 months in 3 children. However, valgus malalignment of the tibia progressed in all 3. One child was treated with resection of a lateral fibrotic band and another with distal tibial epiphysial distraction and realignment. In the fourth patient, who was skeletally mature, a nonunion developed proximally.