Plaque rupture may play an important role in acute cerebral events. Recent technological advances in ultrasonographic systems provide a feasible diagnostic modality of atherosclerotic lesion by clearly visualizing flow conditions and vessel morphology. A 58-year-old man with chronic renal failure underwent duplex Doppler ultrasound in which ruptured plaque on carotid arterial wall was imaged. Color Doppler imaging showed that the plaque shoulder at the proximal site was hit by forward flow to the brain and ruptured. Curling flow in the inner space of the plaque was observed. Carotid arteriography at the corresponding site of ruptured plaque revealed the space within the plaque similarly contrasted. A magnetic resonance imaging of brain performed after identifying plaque rupture revealed small cerebral infarcts at the cerebral cortex. Plaque rupture could be demonstrated by color Doppler imaging at the proximal edge of plaque and curling flow in the intraplaque space may have released small thrombi to vessel lumen. Plaque rupture of the carotid artery may play an important role in the development of small cerebral infarction.