This work deals with the visualization of the arterial sources of the brain by means of an injection of radio-opaque substance into the carotid artery, aided by circulatory block resulting from an increase in the intrapulmonary pressure. Arterial encephalic sources considered as such are: the common carotids, the vertebral arteries, the brachiocephalic trunk and the prevertebral parts of the subclavian arteries. Arterial puncture (percutaneous) is performed in one of the common carotids or, exceptionally, in the brachiocephalic trunk or subclavian artery (prevertebral part). In order to increase the intrapulmonary pressure, the lungs of the patient are inflated with oxygen through a tracheal tube provided with a cuff. A valve placed between the source of oxygen and the tracheal tube allows for a control of the intrapulmonary pressure which must not exceed 75 mm Hg. The injection of the radio-opaque medium done by hand takes from 2 to 3 seconds and must be started as soon as the intrapulmonary pressure reaches the limit of 75 mm Hg previously set on the valve. Digital compression of the injected carotid above the puncture is an accessory resource of remarkable efficiency permitting a sharp and constant visualization of all the arteries of the region. The results of 46 examinations performed according to the technique here described are reported. Not one occurred in this series of patients. Although there are still a few doubtful points and details of the technique that must be improved or modified the method has shown to be easier and safer than its semilars.