The authors demonstrate the facility with which the principal fissures and sulci of the brain can be angiographically localized by reference to characteristic loops and bends in the courses of the branches of the anterior, middle, and posterior cerebral arteries. The study is based upon dissections of 150 human brains in which the arteries of interest were selectively injected. A propos to this anatomic-angiographic correlation the authors also describe the vascular territories of each cortical branch and propose a simple procedure for the evaluation of these territories during cerebral angiography.