Previous treatments for cavernous dural arteriovenous fistulas (DAVF) include transarterial embolization with NBCA and transvenous embolization with platinum coils. This paper presents two cases of cavernous sinus dural arterial venous fistula successfully treated via a transvenous approach with Onyx. Case 1. A 54-year-old man presented with blepharotosis, diplopia and chemosis. Cerebral angiography demonstrated a cavernous DAVF, which was successfully treated via inferior petrosal sinus with a combination of Onyx and platinum coils. Case 2. A 36-year-old woman was admitted after incomplete transarterial embolization of a dural cavernous fistula. The patien's symptoms resolved almost completely after embolization with Onyx-34 via the superior ophthalmic vein. To our knowledge, only two such cases have been reported in the literature. The advantages of Onyx make it an attractive alternative to the various platinum coils already described.