The authors report their experience with the surgical treatment of carotid-ophthalmic aneurysms in 29 cases, and describe their surgical technique. The technique can be summarized as follows. When dissecting the aneurysm, temporary vascular occlusion of the common carotid artery and external carotid artery is done in the neck under the administration of cerebral protective substances. Through a bifrontal craniotomy, wide dissection of the Sylvian fissures and the interhemispheric fissure is performed. When necessary, the anterior clinoid process and the roof of the optic canal are removed. This approach allows for observation of the neck of the aneurysm from various angles, thus facilitating clipping of the neck. There have been no previous reports of direct surgery on carotid-ophthalmic aneurysms using an interhemispheric approach, but this approach provides a much larger operative field and a better exposure of the aneurysm than other surgical approaches.