We report on the safety and efficacy of transarterial and trans venous Onyx embolization in the treatment of dural arteriovenous fistulae (DAVFs) of the cavernous sinus We reviewed the findings from a retrospectively database for 22 patients with cavernous sinus DAVFs who were treated with either transarterial Onyx embolization alone (n = 8) or transarterial and transvenous Onyx embolization (n = 14) over a four year period The mean follow-up period after endovascular treatment was 21 6 months (range 3-42 mths) Total number of embolizations was 27 for 22 patients Two patients were treated transvenously after transarterial embolization All 22 patients (100%) experienced improvement of their clinical symptoms All 22 patients (100%) experienced total obliteration of their DAVFs, as documented by angiography performed at a mean follow-up of 58 months after the last treatment No patient experienced a recurrence of symptoms after angiography showed DAVF obliteration One patient exhibited temporary deterioration of ocular symptoms secondary to venous hypertension after near total obliteration, one had transient V cranial nerve deficit related to transarterial embolization, and two patients exhibited transient III and VI cranial nerve weakness related to transvenous embolization Two patients experienced recurrent symptoms after incomplete transarterial embohzation and underwent transvenous embolization at three and four months Both patients achieved clinical and angiographic cures Transarterial and trans venous embolization with Onyx, whenever possible, proved to be a safe and effective management for patients with cavernous sinus DAVFs