Most patients with intracavernous large and giant aneurysms show cranial nerve signs, and a variety of surgical treatments have been developed. From the viewpoint of multimodality therapy, a combination of bypass and IC ligation or a combination of intravascular therapy and surgery has been performed. <br> We studied 29 consecutive patients with intracavernous large and giant aneurysms during the past 15 years. All the patients presented with cranial nerve signs. Therapeutic modalities for each patient were selected depending on anatomical features of the aneurysm on radiological examinations and neurological/hemodynamic conditions during balloon test occlusion (BTO). <br> ICAs were occluded surgically or endovascularly in 6 patients without bypass surgery. ICA ligation was simultaneously combined with high-flow bypass in 4 patients or with STA-MCA anastomosis in 14 patients, in which 2 patients developed delayed ischemic neurological symptoms due to emboli from the thrombosed aneurysms. STA-MCA anastomosis followed by internal coil trapping of the aneurysm under antiplatelet and anticoagulant therapy was successfully performed in 2 recent patients. Pre-operative neurological symptoms ameliorated when treatment was initiated within 3 months after the onset of symptoms.<br> Favorable clinical outcomes can be expected for patients with an intracavernous large or giant ICA aneurysm treated surgically or endovascularly based on adequate pre-operative radiological, neurological and hemodynamic evaluations. The treatment algorithm for the management of intracavernous large or giant aneurysms of ICA should be reviewed and revised according to the development of new devices and techniques.<br>