Cranial dural fistulae are rare; when they occur, it is usually difficult to detect them at an early stage. With a view to the question of possible progress in diagnosis we now report on seven patients with lateral dural fistulae fed by branches of the external carotid artery. The examination was carried out before selective arteriography using cw-Doppler sonography and colour coded duplex sonography in combination. Sonographic criteria for detection of hyperperfusion take account of flow velocity as well as pulsatility. In all cases hyperperfusion of the external carotid artery was detected. In most of these cases pathologic findings were also observed at the occipital artery, and more rarely in the contralateral external carotid artery or the ipsilateral vertebral artery, in addition. A possible source of error arising from confusion of blood vessels was present with the cw-Doppler sonography, but not for colour coded duplex sonography. Therefore, cranial dural fistulae characterized by a high shunt volume can be diagnosed correctly by indirect Doppler sonographic criteria using cw-Doppler and duplex sonography. Direct visualization of the fistula and its nidus requires additional selective arteriography, in the course of which endovascular embolization may be performed.