Congenital pseudarthrosis of the tibia is a relatively rare but well known entity. Aside from the fibula, which is aften associated with tibia, the clavicle is probably the next preponderant site. Congenital pseudoarthrosis of other bones are extremely rare. We have found 10 cases of congenital pseudarthrosis of either the radius or the ulna in the English literature. Only one case of congenital pseudarthrosis of both bones of the forearm has been reported to our knowledge, A 30 year old man with congenital pseudarthrosis of the radius and the ulna associated with neurofibromatosis was seen at Seoul National University Hospital in March, 1985. Osteosynthesis was successful on the radius, but failed on the ulna. The distal fragment of the ulna eventulally disappeared altogether.