Hypoplasia of the internal carotid artery is a rare congenital anomaly, with only 24 cases of bilateral internal carotid artery hypoplasia reported to date. Here, we present the case of a 48-year-old woman with bilateral internal carotid artery hypoplasia. She had a collateral circulation through the vertebrobasilar system; however given the high pressure flow she developed aneurysmal formations in the posterior communicating artery. To the best of our knowledge, only seven reported cases of internal carotid artery hypoplasia have been associated with intracranial aneurysmal formations.