26 patients admitted with clinical pictures consistent with meso-diencephalic infarction were studied using computerized axial tomography, magnetic resonance imaging and angiography. All of the patients presented symptoms in two of three major categories which comprise the "top of the basilar" syndrome. Lesions in the territory of the basilar-communicating artery were demonstrated in 22 of them. The remaining patients died before adequate neuroimaging documentation was obtained. Overall prognosis appeared relatively good since 80% of the patients recovered completely or incompletely from the ictus. Meso-diencephalic infarction is a very important and not uncommon subtype of cerebrovascular disorder.