The use of the Bailliart ophthalmodynamometer makes it possible to apply increasing, measured pressure to the anesthetized sclera while the observer watches the retinal arteries. This constitutes a rapid, safe test for internal carotid artery insufficiency. Comparison of the ophthalmic artery pressures obtained when the patient is standing with those obtained when he is supine enhances the sensitivity and diagnostic usefulness of the test. Eleven cases are described to illustrate the significance of the results. Indications for ophthalmodynamometry include clinical evaluation of cerebrovascular disease and amaurosis fugax, evaluation of endarterectomies and carotid ligations, evaluation of response to anticoagulant therapy in carotid disease, and investigation prior to arteriography.