We report a 47-year-old male stroke patient with nasopharyngeal cancer NPC) and protein C deficiency. The patient was diagnosed with NPC and received a complete course of radiotherapy. Infarction stroke occurred 28 months after radiotherapy and magnetic resonance imaging of the brain confirmed the diagnosis. Carotid duplex sonography showed 50-79% stenosis in his left internal carotid artery. Coagulation profiles indicated protein C deficiency. After medical treatment and rehabilitation, the patient regained the ability to walk and he could perform most of his daily activities. Radiotherapy-induced carotid stenosis is an exacerbating feature of stroke in patients with protein C deficiency. We suggest early carotid duplex sonography and survey of the coagulation profile to prevent a stroke in patients with NPC. ; 醫學系復健科 ; 醫學系 ; 醫學院 ; 期刊論文