Occlusions of the small intracranial vessels have the unfortunate position of the neglected stepchild in relation to cerebral vascular disease. This neglect is reflected in the disappointing, diagnostic accuracy of cerebral angiography in this condition. Despite the tremendous technical developments in the field in the past few years, in the reported series of angiographic investigations in stroke patients, little improvement has been shown in the percentage of definitive diagnoses obtained. For example, McDowell et al. (8) in 1959 found a negative angiogram in 19 of 68 stroke patients, Bull et al. (3) in 1960 reported negative angiographic findings in 45 of 80 stroke patients, and in June 1966 Balow et al. (1), excluding minor plaques and irregularities, found a positive diagnosis in only 44 of 87 patients. The neglect of the small intracranial occlusion is due in part to the emphasis placed on the extracranial cerebral vessels. While this may be a justifiable approach for the surgeon, the function of the radiologist is to make an anatomical diagnosis, irrespective of the popularity of the disease or the possibilities of definitive treatment. By overlooking the intracranial lesions and attaching undue emphasis to irregularities and minor stenoses of extracranial vessels, a false picture of the individual patient's problem and of cerebral vascular disease in general may be obtained. The importance of intracranial occlusion has been shown by the meticulous studies of extracranial and intracranial vessels recently carried out independently by Moossy (9), and Fisher and his co-workers (6). In a subsequent publication on intracranial arterial thrombosis Moossy stated: The demonstration of intracranial arterial thrombi and the inference that they were responsible for recent cerebral infarcts in 55 per cent of the 142 cases is a finding at variance with certain current concepts of the pathogenesis of cerebral infarcts. While this study does not diminish the importance of the extracranial carotid and vertebral arteries, it does tend to restore the intracranial arterial system to a position worthy of more consideration than it has enjoyed recently. The problem for the conscientious radiologist is not lack of interest in intracranial occlusions of smaller branches but lack of confidence in his ability to diagnose them. There has been little in the literature to encourage efforts in this respect for, although the problem is recognized, systematic studies are few. Taveras (15) suggested the diagnosis of occlusions of the smaller intracranial vessels by seeing retro grade filling of the involved branch Chase and Kricheff (4) stated that distal occlusions may be suspected by stasis in the supplying vessel and occasionally a capillary blush due to collateral vascular formations.