The syndrome of carotid sinus hypersensitivity is cardovascular symptom complex including lightheadedness, transient loss of consciousness, perspiration, pallor, weakness of lower extremities, transient hypotension, bradycardia and seizure, which occurs from firing of hyperactive carotid sinus reflex. Most cases are idiopathic, but maliganant tumors involving parapharyngeal space have been occasionally implicated. We present a case of carotid sinus hypersensitivity due to nasopharyngeal carcinoma invading the parapharyngeal space with bilateral cervical lymphnode metastases(stage IV, $T_4N_2M_0$). The patient experienced several episodes of severe syncope proceeded by blurring of vision, dizziness and nausea, which were used to occur while he was working in erect position. The tumors were markedly regressed by external radiation therapy with successful resolution of syncope.