OBJECTIVE To evaluate the diagnostic efficiency and accuracy of contrast-enhanced transcranial color-coded sonography (CE-TCCS). BACKGROUND TCCS is hampered by insufficient ultrasonic penetration in 20% of cerebrovascular patients. METHODS In 47 patients whose basal arteries could not be assessed adequately, 59 TCCS examinations were performed before and after administration of the ultrasonic contrast agent (CA) Levovist. The assessability of different basal cerebral arteries after CA administration was evaluated off-line. Angiographic records were available from 11 patients. RESULTS Satisfactory investigation of the middle cerebral artery, the anterior cerebral artery, the P1 and P2 segments of the posterior cerebral artery, and the supraclinoid portion of the internal carotid artery siphon was possible in 5.1%, 28.8%, 35.6%, 55.9%, and 47.5% of patients before, and in 84.7%, 91.5%, 93.2%, 94.5%, and 93.2% of patients after contrast enhancement. Stenoses or occlusions of basal cerebral arteries were registered in 28 patients (60%). CE-TCCS diagnosis was confirmed by digital subtraction angiography or magnetic resonance angiography in 10 of the 11 patients, leading to positive and negative predictive values of 0.86 and 1.00. CONCLUSIONS Contrast enhancement improves the diagnostic potential of TCCS significantly in patients with temporal bone window failure, and proved to be a reliable method for detecting middle cerebral artery and siphon occlusion.