Dissecting aneurysms frequently involve the vertebral arteries and their branches, but those involving the posterior inferior cerebellar artery [PICA] and not vertebral artery at all are extremely rare. We present a case of an isolated dissecting aneurysm of the PICA without involvement of vertebral artery. A 54-year-old man presented with dizziness and headache. MR imaging of the brain showed a cerebellar infarction of the left PICA territory. MR angiographic and cerebral angiographic studies revealed a dissecting fusiform aneurysm involving the left proximal PICA. Subsequently, the patient underwent GDC embolization. A postembolization angiogram demonstrated complete obliteration of the aneurysm. In this report, the treatment modalities for this rare condition is described with review of the literature.