Twenty patients with cerebral arteriovenous malformations (AVMs) were followed up by angiography. Of the 20 AVMs, 16 were nontreated and the remaining 4 were residual. The follow-up periods between the two examinations were from 5 to 28 years, with a median interval of 15 years. At follow-up, the size of the AVM had increased in 4 patients (20%), decreased in 4 (20%), totally regressed in 4 (20%), and was unchanged in 8 (40%). In cases of enlarged AVMs, the patients were all young: from 0 to 11 years old at first angiography and from 6 to 30 at second angiography. The decrease or total regression of the AVM occurred in older patients (over 30 years old at second angiography), and the AVMs were relatively small and fed by single or a few feeders. The patient's age and the size of AVM should be considered when operative indications are discussed.