During the past 10 years studies on the clinical examination and the treatment of intracranial arteriovenous aneurysms have been illustrated by ever-increasing series.1,6,8,9,11,16According to our present conception these aneurysms are congenital malformations of the vessels. However, in the majority of cases the symptoms first appear during the second and third decades of life. Symptoms in earlier life are rare. Whether this is an indication that arteriovenous aneurysms increase in size with increasing age or is the result of other factors has not been established. Knowledge up to the present on the growth behavior of these aneurysms is based on a few isolated observations. Olivecrona and Riives8reported a case with a 10-year interval between arteriographic studies. The arteriovenous aneurysm was localized in the posterior part of the right frontal region and appeared to have increased in size. Shenkin et al.14also observed an increase in size