Objective: The embolic agents currently used for the treatment of AVMs are n-butyl cyanoacrylate (NBCA) and ethylene-vinyl alcohol copolymer (ONYX). The purpose of this study was to examine the overall NBCA and ONYX embolization-related complication rate. Methods: We retrospectively reviewed 147 consecutive patients with cerebral AVMs treated mainly with endovascular NBCA and ONYX embolization. Demographics, including age, sex, presenting symptoms, and angiographic factors including AVM size, deep venous drainage, and involvement of eloquent cortex were recorded. Number of pedicles embolized, the obliteration rate, and any complications were recorded. Complications were classified as the following: bleeding and ischemic complications. The ischemic complications were also classified as transient neurologic deficit, and permanent deficits. Modified Rankin Scale (mRS) scores were collected pre- and postembolization on all patients. Univariate regression analysis of determinants of complications was performed. Results: We reviewed 147 patients with BAVM (58.5% male; mean age +/- SD at treatment: 27.5 +/- 11.1years) treated with endovascular embolization. Two hundred twenty embolization, 144 NBCA and 76 ONYX embolizations were performed. Complete obliteration of BAVMs were achieved in 29 patients (19.7%). Additional gamma-knife radiosurgery were performed for 32 (21.8%) patients. There were 5 Spetzler-Martin grade I (3.4%), 20 grade II (13.6%), 54 grade III (36.7%), 44 grade IV (30%), and 24 grade V (16.3%) AVMs. There were a total of 7 (4.8% per patient, 3.2% per procedure) complications. There were bleeding complications in 2 patients (1.4% per patient, 0.9% per procedure), transient neurologic deficits in 4 (2.7% per patient, 1.8% per procedure) and 1 permanent deficit (0.7% per patient, 0.5% per procedure). Of the 147 patients, 141 (95.9%) were mRS 0-2, 6 (4.1%) were mRS = 3 at discharge. Univariate analysis of risk factors for embolic agent showed that ONYX was not significantly associated with complications (X(2) = 0.3, P > 0.5). Conclusions: Embolization of brain AVMs is safe, 95.9% of patients had excellent or good outcomes at discharge after AVM embolization using liquid embolic agents, with a complication rate of 4.8%. ONYX embolization was not associated a higher rate of complications comparing with NBCA embolization. (C) 2010 Elsevier Ireland Ltd. All rights reserved.