Embolism from the aneurysmal sac is a rare but possible manifestation of intracranial aneurysm; thrombus formation is probably related to the combined action of turbulent flow and a 'stagnant zone'. Three cases are presented: 2 with giant aneurysms (1 internal carotid and 1 sylvian) and 1 with a large aneurysm of the middle cerebral artery. In the latter, surgical treatment was performed, while in the others a conservative therapy was preferred. No ischemic manifestations were observed in the follow-up.