Thirty-three of 129 patients who incurred isolated ophthalmic migraine had monocular attacks of scotomatous visual field loss. Fifteen of 33 patients with monocular attacks had immediate or remote evidence of vascular disease. Four patients had carotid bruits on the same side as the monocular attacks and low ophthalmodynamometer readings. One patient had ischemic optic neuropathy and two had atheromatous disease (advanced stage in one patient). Forty-five percent of the patients with monocular attacks and only 13% of the remaining patients with homonymous attacks had vascular complications. This represents an important finding even in such a small group of patients. It is felt that, whether the vascular problems are trigger mechanisms or coexistence pathology to the migraine-type attack, one should strongly suspect such an association when a patient describes a monocular attack and one should look for a possible vascular explanation other than migraine.