This paper concerns 23 cases of arterial occlusion. The affected artery were primitive carotid (2 cases), internal carotid (16), anterior cerebral artery (2), the Sylvian artery (3). Frequency of the arterial occlusion related to age and sex, symptomatology and diagnostic methods are studied. A marked dominance in male patients was foynd. The extremes of age in the patients examined were 10 months and 56 years; the other patients had ages between 20 and 50 years. Hemiplegia was the most frequent symptom (21 patients). The authors are convinced that, to discard the cases of transitory occlusion due to spasm, it is necessary to visualize the same aspect in subsequent examinations, mainly when the visible section of the occluded artery does not show any characteristic deformity. In 12 cases, for checking purpose, angiography in the opposite side was performed; no accident occurred in these cases. The heterolateral angiography represents not only a cross-examination of vascular occlusion, but permits to study the compensatory circulation.