In a recent publication, reporting the sixth case of aortic angiosarcoma, probably induced by the implantation of a dacron vascular prosthesis, Weiss et al. have done a literature review concerning the association between the presence of vascular prostheses and the onset of mesenchymal neoplasms. Although they consider the incidence of this association very low, they also point out the hypothesis, largely supported by experimental studies, that vascular prostheses can play the role of aetiological co-factor or factor in the onset of these tumors. We consider useful to report a case of malignant fibro histiocytoma arising around a femoral vascular prosthesis in a patient operated on for aneurysm of the femoral artery.