To determine carotid cavernous fistula associated with choroidal detachment after cataract surgery. A 77-year-old woman underwent cataract surgery in both eyes. Postoperatively, proptosis and dilation of episcleral vessels in her left eye occurred and gradually increased. One month later, choroidal detachment developed in her left eye. Computed tomography showed an enlarged superior ophthalmic vein. Selected cerebral angiography showed fistulas between the megingeal branches of both the internal and external carotid arteries and the cavernous sinus. After the neurosurgical treatment, these symptoms disappeared. The development of carotid cavernous fistula after cataract surgery, as demonstrated in our patient, may be uncommon. [Ophthalmic Surg Lasers 1998;30:160-162.] Carotid cavernous fistula (CCF) is an abnormal communication between the internal carotid artery and the cavernous sinus. Ocular manifestation of the fistula includes proptosis, pulsation of the globe, orbital bruit, episcleral vein dilation, and chemosis. CCF is divided into spontaneous or traumatic by cause and direct or dural by angiographic findings. To our knowledge, CCF development after cataract surgery may be uncommon. We recently examined a patient with such a condition.