Of 11, 779 consecutive CT examinations of the head 74 patients of infarctions in 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 terriories 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 and the 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 case 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.