The management of asymptomatic carotid stenosis remains unclear in terms of screening as well as of treatment. The degree of carotid stenosis is not enough to clarify the debate. It seems useful to search among severe carotid stenosis parameters indicating higher ipsilateral stroke risk. Duplex ultrasound and transcranial Doppler offer this opportunity with a diagnostic battery allowing to evaluate hemodynamical risk (degree of stenosis, common carotid flow, MCA signal, cerebral vasoreactivity), thrombo-embolic risk (echostructure of the stenosis, micro-embolic signals, HITS) and progression of the stenosis.