In a 64-year-old male, recurrent syncope, hypotension and bradycardia developed repeatedly. The systolic blood pressure fell and could not be measured by auscultation method and the heart rate decreased to under 20 bpm. He recovered from unconsciousness in several minutes. No precipitating cause was apparent for such episodes. Physical examination revealed swollen lymph nodes in the upper cervical regions. Carotid sinus massage caused a fall of systolic blood pressure by 40 mmHg and the P-P interval lengthened to 1.96 sec. The otolaryngeal examination showed neoplasma in the pharynx. He received irradiation therapy on the primary lesion and the bilateral metastatic lesions. After irradiation (4,000 rad), the paroxysmal hypotension and bradycardia disappeared concomitantly with the reduction in size of the metastatic tumor. Hypersensitivity to carotid sinus massage, however, remained unchanged. In this case, the metastatic tumor around the carotid sinus seemed to be related to the syncope and the hemodynamic collapse.