This chapter presents the definition, epidemiology, diagnosis and principles of management for arteriovenous malformations (AVMs). The primary goal of AVM management is to assess the overall risk of the patient, and then develop a management plan that minimizes risks, i.e., deciding whether obliteration or observation is safest. The primary goal of obliterative AVM treatment by any modality is the prevention of hemorrhage. The epileptogenicity resulting from a hemorrhage and from hemosiderin deposition has been documented. Treatment of AVMs, with surgery, radiation, embolization, or a combination of these, can cause new seizures in some patients with AVMs, albeit with a risk which is much smaller than the risk of the AVM itself causing seizures. While the primary goal of AVM treatment is the prevention of hemorrhage, several retrospective series have also demonstrated a benefit in seizure outcome with AVM treatment with surgery, radiation, embolization, or multimodality treatment.