An international consensus meeting to determine criteria for the characterization of extracranial carotid artery stenosis was held in Paris on December 13–14, 1996. Recommendations are the following if the degree of the stenosis and the precise location of the stenosis are well defined. Ultrasonic Doppler duplex methods 5 MHz capable of insonating up to 4 cm and retrievable documentation of relevant findings. Computed tomographic angiography 2 mm in size. Angiography may identify gross calcifications and large ulcers defined in two classes: 1 – large (2 mm depth by 2 mm width) and 2 – complex with multiple craters. Magnetic resonance imaging with or without angiography may play a role in the future. In vitro studies show that MR can demonstrate plaque components such as fibrosis, calcification, hemorrhage and necrotic core, but current technical limitations related to resolution and motion artifacts prevent this from being implemented in vivo. Pathological studies require en bloc surgery. Component areas should be calculated from their length and width, and ulcerations measured from their width. The risk of cerebrovascular ischemia is clearly related to the degree of stenosis. Factors of individual importance for higher risk include in descending importance: evidence of progression, surface ulceration and low echogenicity. Texture is still under investigation as a prognostic