The purpose of this report is to describe, based on the experience with 50 patients, transcranial colour-coded duplex ultrasonography and to evaluate its practical potential in the routine examination in comparison with conventional transcranial Doppler ultrasonography. Under visual control, the Doppler angle between the ultrasonic beam and the flow direction can be adjusted. The mean angle of incidence in the middle cerebral artery was 33 degrees +/- 15 degrees, in the anterior cerebral artery 35 degrees +/- 17 degrees, in the posterior cerebral artery 45 degrees +/- 18 degrees and in the basilar artery 15 degrees +/- 14 degrees. The measurements of blood flow velocity under consideration of the angle of incidence resulted in 15%, 18%, 30% and 3% respectively higher velocity values. Examples of pathologic findings demonstrate the practical potential of this noninvasive method.