Background In the past 5 years, new treatment materials and techniques offering a different concept in endovascular treatment have been described for cerebral arteriovenous malformations ( CAVMs). The aim of this study was to assess the endovascular treatment of CAVMs by using a liquid embolic material, Onyx ( Micro Therapeutics. Inc., Irvine, CA, USA). Methods From September 2003 to September 2004, Onyx was used to treat 22 patients with CAVMs. Ten AVMS were located in functional areas, 8 in deep cerebral areas, and 4 in the cerebellar hemisphere. The size of CAVMs was about 3 cm in diameter in 5 patients, 3 -6 cm in 11, and more than 6 cm in 6. Results In the 22 patients, Onyx embolization was successful. Nidus occlusion was complete in 3 patients, > 90% in 8, > 80% and < 90% in 6, and > 50% and < 80% in 5. Complications included transient neurological deficits in 2 patients, and adherence of microcatheter to the site of injection in 2. Conclusions Being non-adhesiveness, Onyx is a safe and satisfactory embolic material in the treatment of CAVMs. But its long-term efficacy awaits further follow-up.