It would seem that most reports of post-irradiation extracranial cerebrovascular disease concern the long-term effects of this form of therapy. Three such cases are described here. The features peculiar to this form of disease are its severity and very considerable extent. Radiologists and vascular surgeons contribute heavily to its diagnosis. Whilst it would appear that rarely in early cases a type of vascular lesion peculiar to radiation damage has been encountered, for the most part reports have emphasised the presence of very extensive and accelerated premature vascular aging and atherosclerosis as a fundamental lesion probably involving all laminae of the vessel. In addition extensive perivascular fibrosis and overlying post-irradiation skin atrophy can be seen. Therefore in patients presenting with cerebrovascular pathology even years after receiving radiation therapy, the neurologist and vascular surgeon must be prepared to recognise that extensive damage may underlie the patients' symptoms and that investigation and surgical repair may have to be undertaken forthwith if at all practicable.