Objective: Fenestration is a vascular variation that begins with a common origin, then splits into two parallel luminal channels that rejoins distally. We aim to evalute the frequency of cerebral arterial fenestrations and their association with cerebral aneurysm by computed tomography (CT) angiography. Methods: We retrospectively analyzed cerebral CT angiography of patients obtained between January 2017 and December 2020. Patients older than 18 years-old, without known vascular disease and previous surgery or interventional treatment were included the study. The location of the fenestration and aneurysms were noted. Results: CT angiographies of 887 patients (mean age 54.8 years, range 18-63 years; 405 women and 482 men) were evaluated. 164 fenestrastions found in 152 patients for a detection rate of 17.1%. Anterior communicating artery fenestrations were the most common (51.2%), followed by vertebrobasilar system fenestration (28.7%). In our study, no significant relationship was found between fenestration and aneurysm, regardless of localization (p>0.05). However, in the coexistence of fenestration and aneurysm, these are commonly located at the same localization (p: 0.005). Conclusion: Cerebral artery fenestration is an uncommon and mostly affects the anterior communicating artery and vertebrobasilar system. Cerebral artery fenestrations could be associated with aneurysms at the fenestration site. Further attention should be paid to the coexistence of aneurysm once intracranial artery fenestration has been found.