Four cases of the occlusive arterial disease "moyamoya" type, are reported with comments on the clinical, roentgenological and embriological aspects. The clinical onset in all four cases was of isquemic type, in spite of different ages (2 adult male, one young adult female, 1 child female). Some particular symptoms are analysed, mainly the constant complaint of episodes in which the patient is, suddenly, extremely tired. The causes of this episodes are thought to be due to suddenly lowering of the cerebral perfusion in the disease. The importance of the radiological appearance is emphasyzed. The plain roentgenographic films, the site of the occlusion, the associated vascular malformations, the collateral circulation and the site of the vascular nest, are discussed. Some embriologic aspects of the etiology including the variable time onset of the pathologic process are also discussed.