Arteriovenous malformations (AVMs) dramatically alter normal cerebral circulatory dynamics. Clinical and radiographic data from 62 patients were analyzed to determine their impact on total brain blood flow (TBF) measured by single-photon emission computed tomography. 48% of patients presented with hemorrhage and 34% with progressive deficits. 37% had angiographic steal and 21 % developed postoperative hyperemic complications. 40% were under 30 years old, 45% were between 30 and 50 years of age, and 15% were over 50. TBF was less than 70 ml/100 gm/min in 32% of patients, between 70 and 84 ml/100 gm/min in 40%, and greater than 84 ml/l00 gm/min in 27%. Female patients had higher TBF than males; 42% of females but only 17% of males had values greater than 84 ml/100 gm+frsal;min (p < 0.05). A trend toward decreased TBF with advancing age was noted. Intracranial hemorrhage was associated with lower TBF; 47% of patients with hemorrhage and 19% of those without had TBF of <70 ml/ 100 gm/min (p < 0.05). 89% of patients with AVMs less than 5 cm in diameter had TBF of ≤84 ml/100 gm/min, and 65% of those with larger AVMs had similarly low flows (p < 0.05). A trend toward lower TBF was observed in patients with unfavorable outcomes.