Cerebral arterial occlusion is a fairly frequent condition. We have diagnosed nine cases by cerebroangiography in the past two years, and there are many patients not given this special examination.Precise diagnosis has become more important as advances in therapy make prognosis more hopeful. The symptoms are various according to the location and degree of occlusion and the amount of collateral circulation.Angiographic diagnosis is not difficult, but repeated demonstration of the block should be insisted on. This is best done with multiple exposures after a single injection of contrast medium. We use 7 cc. of 50 per cent Hypaque(R) and one exposure per second through the arterial, capillary and venous phases. The films should cover the entire head and neck lest an occlusion in the common carotid be overlooked. We have found the Schonander biplane apparatus very satisfactory, using films 14 inches square and exposing them in anteroposterior and lateral projections simultaneously.