We report the singular case of an exceptionally large giant communicating artery aneurysm successfully treated with a direct surgical approach. The clinical presentation was a relatively short history of frontal headache. In the pre- and postcontrast CT scans the lesion mimicked an intracranial tumor. At surgery the intraluminal thrombus was partially removed with an ultrasonic surgical aspirator; the decompression allowed the isolation and subsequent temporary dipping of the tracts A1 and A2 of both the anterior cerebral arteries. It was then possible to complete the thrombectomy and to dip the neck of the aneurysm. The report emphasizes the indispensable role of MRI for the accurate diagnosis of giant intracranial aneurysms and the recent improvement of the surgical results concerning this category of aneurysms (mainly related to the present wider availability of technical surgical instrumentation).