The natural history of patients with arteriovenous malformations (AVM's) suggests that serious morbidity associated with AVM's in functional areas is likely to be much greater than in silent areas. Various modes of treatment of AVM's in functional areas, including direct surgical intervention, embolization, and irradiation, have been considered to carry high risks. The authors advocate direct surgical intervention to these AVM's via a microsurgical technique based on knowledge of the hemodynamic anatomy of AVM's. The technique is designed to circumscribe the AVM without removing any surrounding cortical tissue or white matter and to preserve microcirculation in the functional area. Controlled hypotension (mean arterial blood pressure 40 to 60 mm Hg) is appropriate to enhance the safety of surgical procedures without causing metabolic and electrophysiological dysfunction. Another means to prevent neurological complications is multi-staged resection of larger AVM's, which permits obliteration compartment by compartment. This technique has the advantage of maintaining circulatory sufficiency in the functional area. There was no mortality among 56 patients who underwent the surgical procedure described. Of those, 55 patients resumed their preoperative occupation and one patient became self-sufficient.