The formation mechanisms of rare intracranial aneurysms are various, which lead to various kinds of treatment methods. The present article summarized the pathogenesis, pathologic changes in vascular walls and imaging features of rare intracranial aneurysms including segmental ectasia, aneurysms with dissection, aneurysms with intramural hemorrhage, mycotic aneurysms, aneurysms related to HIV, neoplastic aneurysms and traumatic aneurysms through literature review.