The case of a 41-year-old man experiencing profuse nosebleeds through the right nostril is reported. An infraclinoid aneurysm of the left internal carotid artery opening into the sphenoid sinus was found. No collateral circulation through the anterior communicating artery could be demonstrated in the angiograms. The left internal carotid artery was slowly clamped in the neck to a lumen of about 1 mm. The patient nevertheless suffered recurrent haemorrhages; a new angiogram showed good circulation through the stenosis, and an increase in the size of the aneurysm. The artery was then completely occluded. There was no neurological deficit and no recurrence of bleeding.