Von Recklinghausen's neurofibromatosis is a kind of neurocutaneous syndrome characterized by skin, nervoussystem, neuromusculoskeletal manifestations. Most central and peripheral nervous neoplastic lesions in neurofibromatosis are benign but have a significant potential for malignant transformation such as neurofibrosarcoma, neurogenic sarcoma, malignant schwannoma. And it is a relatively common disorder but malignant change with radiologic findings has been reported rarely in korea. Recently we experienced theree cases of malignant degeneration in neurofibromatosis and confirmed by pathology. So we report the cases with review including radiologic findings.