Angio-tomography is a selective radiological method which can be used to complement serial angiographs in order to demonstrate better detail. This results from the fact that selective levels can be demonstrated without super-imposition of bone or other vessels. Angio-tomography combines the advantages of tomography, subtraction and selective procedures. The method has been used for all types of intracranial disease; aneurysms and angiomas are the most common conditions for which angio-tomography has been employed. The present paper is based on a total of 60 cerebral aneurysms and angiomas in various situations; angiotomography was indicated for these amongst a larger material of intracranial vascular malformations in which the diagnosis was possible without its use. The indications consist of: 1) Demonstration of very small aneurysms and their differentiation from vessel loops, 2) Demonstration of the origin of an aneurysm which is situated at the confluence of several major vessels, 3) Point of origin of a so-called hugeaneurysms which cannot otherwise be shown by oblique views, 4) Demonstration of so-called micro-angiomas and of the afferent and efferent vessels in central arterio-venous malformations. Unusual aneurysms of the internal carotid artery, of the anterior choroidal and vertebral arteries are described. Some new concepts in the localisation of aneurysms of the anterior communicating artery are discussed. Many of the examinations were carried out with an angio-tomographic apparatus made in the department.