Cranial nerve damage following head and neck radiotherapy is an unusual event. Cranial neuropathy following concurrent chemotherapy and radiotherapy is unreported. The authors report a case of a 54-year-old man treated with curative chemotherapy and radiotherapy for a stage III nasopharyngeal carcinoma who developed an unilateral hypoglossal nerve palsy five years after therapy. Follow-up examination and magnetic resonance imaging (MRI) show no evidence of recurrent disease. Hypoglossal nerve injury occurring after head and neck radiotherapy is an indirect effect due to progressive soft tissue fibrosis and loss of vascularity. This process develops over years leading to nerve entrapment and permanent damage. Cranial nerve palsies, including damage to the hypoglossal nerve, can develop years after therapy with no evidence of tumour recurrence. Chemotherapy and radiotherapy have improved progression-free and overall survival in advanced nasopharyngeal cancer. As more patients achieve long-term tumour control following chemotherapy and radiotherapy, we must be cognizant of potential late injury to cranial nerves.