In a post-mortem study to determine the accuracy of angiography in defining atheromatous disease of the origin of the internal carotid artery, 64 carotid bifurcations were filled with a mixture of gelatin and contrast medium, X-rayed, cleared for pathological study, and assessed by a neurologist and a vascular surgeon. Agreement between the two observers on the X-ray appearances was 87.5% and between the agreed X-ray interpretation and the macroscopic pathological findings 78.6%. Closest agreement was seen with normal and stenosed vessels. Difficulties were encountered with lesser changes due to plaques and ulceration. Since the decision to recommend carotid endarterectomy in patients with a history of transient ischaemic attacks depends on the angiographic findings, knowledge of the accuracy of angiography can be critical.