Four cases of malignant peripheral nerve sheath tumour showing vascular differentiation are described. One case was associated with neurofibromatosis 1 and contained angiosarcomatous, cartilaginous and rhabdomyoblastic elements. The other cases occurred in patients without neurofibromatosis and showed a spectrum of vascular lesions ranging from lobulated, haemangioma-like structures to angiosarcoma. These are the first recorded examples of this phenomenon not associated with neurofibromatosis. Immunohistochemical examination demonstrated the endothelial nature of the lesions in all cases and revealed cells positive for alpha-smooth muscle actin, probably pericytes, closely apposed to the endothelium.