An increasing number of patients with head and neck squamous cell carcinoma and other lesions are treated with high dose radiotherapy. An increase in survival rates is being reported along with a younger patient demographic. The long-term effects of treatment on the carotid arteries and hence cerebral function are not well recognised. The authors followed 103 patients undergoing head and neck irradiation for a variety of lesions for more than five years. Baseline protocol (before radiotherapy) included screening for cerebrovascular risk factors and intima media thickness measurement of carotid arteries by ultrasonography. Follow-up assessment after radiotherapy included screening for cerebrovascular risk factors, cerebrovascular events, neurological examination with gait and balance tests, extensive neuropsychological examination, self-reported questionnaires, ultrasonography of the carotid arteries with measurement of intima media thickness and elastography, magnetic resonance imaging of the brain and magnetic resonance angiography of the carotid arteries. The final results are not yet published but the mere amount of data is likely to improve our understanding of the causes and consequences of long-term cerebral and vascular changes after radiotherapy of the neck. These data will be helpful to develop a protocol for accurate diagnosis and aid preventive strategies to avoid long-term neurological complications in patients undergoing radiotherapy treatment.