Spontaneous dissection of the internal carotid artery is typically associated with cerebral vascular infarction along the anterior and middle cerebral distribution, whereas occipital infarction is usually related to posterior circulation abnormalities. Hemianopsia with occipital infarction related to carotid artery dissection has therefore rarely been reported. A 40-year-old woman in whom acute-onset hemianopsia developed, related to occipital infarction secondary to internal artery dissection, is described. This atypical association is explained by anatomic variations of the posterior part of the circle of Willis. Neuroimages showed occipital infarction related to internal carotid artery dissection associated with hypoplasia of the proximal portion of the cerebral posterior artery (P1). The anatomic correlation of this atypical association and a review of the literature are presented.