Transcranial duplex sonography has the capacity of detecting venous flow as in the transverse sinus. During a 6-month period, 28 consecutive patients (mean age 55 y) with a clinically suspected diagnosis of cerebral sinus thrombosis were included in the study. All patients were examined using 3-D ultrasound equipment within 24 h of having undergone either venous computerized tomography (CT), venous magnetic resonance imaging (MRI) or cerebral angiography. A total of 22 healthy patients had a normal venous CT, venous MRI or cerebral angiography of both transverse sinuses. Before echo contrast enhancement, the transverse sinus could be visualized in only 2 of these 44 sinuses (22 patients). A total of 6 patients with an unilaterally missed transverse sinus in 3-D ultrasound suffered from sinus thrombosis (n = 3), hypoplasia (n = 2) or aplasia (n = 1) of the unilateral transverse sinus in neuroradiological tests. In none of the patients with an thrombosis of the transverse sinus did ultrasound contrast media application improve the visualization of the affected sinus. Our study confirms that the normal transverse sinus, insonated through the contralateral temporal bone, often cannot be visualized without the use of contrast agents. With transcranial 3-D duplex sonography, a differentiation between thrombosis, hypoplasia and aplasia of the sinus was not possible.