A middle-aged man with pain in the right eye and right side of the neck was brought to the emergency department one hour after the onset of left-sided weakness. Computed tomography (CT) showed hyperdense right middle cerebral artery (MCA). On transcranial Doppler (TCD), occlusion of the right MCA and right internal carotid artery (ICA) was found. Thirty minutes after thrombolytic therapy was initiated, engagement of collateral circulation through the anterior communicating artery (AComA) was shown by TCD. Caro-tid duplex examination confirmed occlusion of the right ICA with intimal flap and intramural haematoma. CT angiography revealed flame-like occlusion of the right ICA, and occlusion of the right MCA with collateral supply from the left to right anterior cerebral artery through the AComA. Recanalization of the MCA and ICA was evident on both CT and ultrasound. Frequent ultrasound monitoring is useful for haemodynamic evaluation of carotid artery dissection, while TCD plays an important role in real-time monitoring of flow changes of intracranial vasculature.