Of 11,779 consecutive CT examinations of the head, 74 patients of infarctions in the cerebellum and brainstem were retrospectively reviewed to define the most typical distribution of infarctions in the different vascular territories. More limitation for knowledge of vascular territories in this area is noted, but many cases reveal characteristic findings consistant with one vascular territory. Of 74 cases, 41 were male and 33 were female, andthe age ranged from 2nd to 8th decades. Of 74 cases, the lesion of PICA territory was observed in 29 cases(38%),SCA territory in 26(36%), brainstem in 25(34%) and watershed zone in 14(19%). Twenty-one cases have infarctions of two different vascular territories. The SCA territory is the most extensive territory and includes the largest part of the deep white matter.