BACKGROUND: Although various bypass options for the surgical treatment of middle cerebral artery aneurysms have been described, little has been reported about similar options for complex aneurysms of the anterior cerebral artery. CASE DESCRIPTION: We report the case of a 15-year-old adolescent girl, in whom a giant A1 segment aneurysm was successfully treated with aneurysm resection followed by saphenous vein interposition grafting. CONCLUSION: Recognizing the option for a bypass can be the key to success in the surgical management of complex intracranial aneurysms. A potential donor vessel of appropriate size (either arterial or venous) should be prospectively identified. Interposition grafting is technically feasible for proximal anterior cerebral artery aneurysms, although technically demanding.