Multiple cerebral aneurysms reportedly account for 14-33 % of all cerebral aneurysms. The incidence of multiple aneurysms has been increasing with development of radiological diagnostic tools such as magnetic resonance angiography, digital subtraction angiography and three dimension computed tomography. However, multiple aneurysms arising from same parent artery are uncommon. We have found only a few references as to diagnosis and surgical treatment of such lesions in the literature. Multiple separate aneurysms on same parent artery have been found most frequently on internal carotid artery 2, and then from middle cerebral artery (MCA). Those lesions arising from anterior communicating artery (ACoA) are rare. We report 7 cases (5.21%) of multiple aneurysms developed separately on ACoA and describe angiographic and operative finding of these rare lesions. One hundred and thirty four ACoA aneurysms were operated in our hospital from May 1997 to November 2004. There were only 7 patients with multiple aneurysms on ACoA. Out of 7 cases, four were diagnosed preoperatively and the other 2 were found intraoperatively. Multiple aneurysms may be associated with familiar aneurysms or arteriovenous malformations, however, there was no such case in our series. All patients were treated successfully with single or multiple clippings. Despite the advanced technology in radiological examinations, these lesions may not be detected on preoperative study. Close proximity or smaller size of the lesion may be responsible for the preoperative false negative angiographic findings. It is recommended to keep this possibility in mind during aneurysm surgery. Careful dissection is mandatory to ensure the completeness of aneurysm surgery.