The purpose of this study was to present the long-term clinical and angiographic follow-up (FU) in 26 consecutive patients with giant/large aneurysms (G/LAs) of the internal carotid artery (ICA) treated by parent artery occlusion (PAO). Twenty-two of 26 G/LAs of the ICA were treated by PAO when a balloon test occlusion prior to occlusion of the ICA was tolerated. Clinical and angiographic FU were available in, respectively, 20 and 18 patients with a mean delay of 6.1 years (range 1.5–11). At long-term FU, clinical symptoms had disappeared in 75% of the patients, partially regressed in 10%, and remained unchanged in 15% of cases. No patient presented worsening of clinical symptoms or intracranial bleeding. Fifteen patients presented a modified Rankin scale score of 0 and five patients a score of 1. On imaging FU, persistent occlusion of the PA was observed in 17/18 cases. One case of aneurysmal recanalization was observed at long-term FU. PAO was well tolerated in all patients. On angiographic FU, no new lesion was detected, except the growing of a pre-existing aneurysm located on the carotid siphon contralateral to the occluded vessel. Our study demonstrates that occlusion of the parent artery for giant/large ICA aneurysms remains a safe and effective technique with good clinical and angiographic outcome at long-term FU.