To date, little attention has been paid to the study of the venous system by means of transcranial Doppler ultrasound. The objective of our study was to learn how to localize cerebral blood flow and find the normal values of different ultrasonographic parameters.We studied 20 healthy persons in whom the arterial system of the circle of Willis had previously been shown to be normal. Transcranial Doppler scan was done with the person lying face upwards, using a transtemporal 2 MHz catheter. In the study we included persons in whom at least one of the two veins could be studied unilaterally.We studied twelve men and eight women aged between 25 and 78 years. The basal vein of Rosenthal, localized bilaterally in 70% of the cases, was identified as a wave of low pulsation between segments P1 and P2 of the posterior cerebral artery, going away from the catheter at a speed of about 11 cm/second. The middle cerebral vein was found bilaterally in only 35% of the cases as a wave near to the middle cerebral artery but in the opposite direction, at an average velocity of approximately 11.7 cm/second and of low pulsation.In spite of the technical problems, which can be solved using contrast agents, it is possible to study the cerebral venous system by means of transcranial Doppler. Our Unit is the first in Spain to show this. We therefore wish to promote the use of transcranial Doppler in cerebral venous disorders.