A 32-year-old man had suffered episodes of loss of consciousness since childhood. He was admitted to another hospital because of three syncopal episodes in one day. He was referred to our hospital because of asymptomatic multiple lacunae indicating cerebral infarction on magnetic resonance imaging. He lost consciousness with convulsion followed by a 70-second interval of cardiac arrest during blood sampling. He reported the onset of his usual prodromal symptoms after 1 min in the 80 degrees head-up tilt position. He lost consciousness 2 min after returning to the supine position. Electrocardiography demonstrated a 10-second interval of cardiac arrest. Magnetic resonance angiography, carotid arterial echography, brain perfusion scintigraphy, and laboratory chemistry and hematology examinations identified no significant findings. Cerebral infarction had occurred in watershed areas, so hemodynamic change during cardiac arrest may be the main cause of the infarctions. He suffered no further syncopal or presyncopal episodes after implantation of a DDD pacing system.