It is suggested that there is a group of cases of congenital angulation of tubular bones in which the lesion is a defect of ossification of the primary cartilaginous anlage and in which neurofibromatosis is not implicated. It appears that in this group the prognosis with regard to the resolution of deformity and the prevention of pseudarthrosis with conservative treatment or relatively simple surgical procedures is better than that in the neurofibromatous type.