OBJECTIVE: To determine the incidence of fenestrations from multislice spiral computed tomography angiography (CTA) series and to establish the possible association of fenestrations with aneurysms and other vascular diseases of the brain. MATERIAL AND METHODS: Four hundred and eighty-six persons who had undergone brachiocephalic artery (BA) CTA for different clinical indications were selected for retrospective analysis. Postprocessor data processing was made to detect extra- and intracranial artery fenestrations. Saccular and fusiform cerebral aneurysms, arteriovenous malformations (AVMs), and venous angiomas were detected in addition to fenestrations. When aneurysms were concurrent with fenestrations, their locations were compared. RESULTS: Among the 486 patients, fenestrations were revealed in 50 (10.3%) cases, of which there were 46 (9.5%) intracranial artery fenestrations and 4 (0.8%) vertebral artery (VA) ones in the extracranial segments. Aneurysms of different locations were found in 163 (33.5%) patients. Venous angiomas of different locations were seen in 9 (1.9%) persons; AVMs were observed in 21 (4.3%) patients. Fifty-four multiple fenestrations were identified. The bulk of fenestrations were located in the area of the anterior communicating artery (ACA) in 28 (51.9%) patients. Aneurysms were found in 11 (22%) patients with fenestrations. Aneurysms were detected in 152 (34.9%) of 436 patients without fenestrations. The incidence of aneurysms was not statistically different in patients with and without fenestrations (p > 0.05); moreover, aneurysms were somewhat more common in patients without fenestrated vessels. Aneurysm located in the area of fenestration was in only one (9.1%) patient. In other cases aneurysms were located in the vessels having no fenestrations. Aneurysms were relatively frequently encountered in 5 (45.5%) patients with BA fenestration. There was no statistical difference in the incidence of AVMs in the fenestration and non-fenestration groups. Venous angiomas significantly more frequently occurred in patients with fenestrations (p < 0.05). CONCLUSION: CTA findings showed fenestrations 10.3% of patients. Fenestrations were located most frequently in the area of ACA and less frequently in the area of BA and middle cerebral artery. Those of other locations, concomitant and extracranial ones, were very rare. According to our data, there was no direct relationship of fenestrations to arterial aneurysms and AMVs. When fenestrations were in the area of BA, the incidence of aneurysms increased up to 45.5%. Venous angiomas occurred more commonly in patients with fenestrations.