In 25 patients with cerebral arteriovenous malformation (AVM) computer tomography (CT) was compared with dynamic and static intravenous radionuclide angioscintigraphy (99mTc-labelled red blood cells). The diagnosis was verified by arteriography performed 2-20 years prior to this study. Scintigrams and CT-scans were evaluated 'blindly' by independent observers after pooling of the patient studies with 20 and 20 control studies, respectively. Only images strictly characteristic of AVM were classified as positive. The nosographic sensitivity of both methods was about 70%, in a few patients they were supplementary. Neither CT nor scintigraphy were able to detect lesions of less than 2 cm diameter. The methods seem to be of equal and rather high specificity, and are both well suited as screening procedures. CT provides additional information as to other intracranial abnormalities. The screening method of first choice when AVM is suspected may be CT or angioscintigraphy, depending on availability of equipment and expertise.