Transverse/sigmoid sinus (TS) is the most common location for cerebral dural arteriovenous fistulas (DAVFs). Most of them are cured by venous embolization or a combination of arterial embolization and surgery/radiosurgery. Our goal was to reconsider the endovascular treatment strategy of TSDAVFs according to the new possibilities of arterial embolization using Onyx-18. Nineteen patients with TSDAVFs were included in a prospective study between 2004 and 2007. Three of them had type I, four had type IIa, six had type IIa+b, three had type III, and three had type IV fistulas. Three presented with subarachnoid hemorrhage. The approach routes, angiographic results, complications, and clinical outcome were assessed. The mean clinical follow-up period was 32.5 months. In one patient, the DAVF had been obliterated spontaneously at ten month follow-up. Complete angiographic cure was obtained in nine cases with one case of progressive thrombosis. Of these ten cures were achieved after a single procedure in seven out of ten patients who had not been embolized previously. Three patients were cured with sinus packing with prior arterial embolization. Among these 19 patients, 15 underwent follow-up angiography which confirmed the complete cure. Partial occlusion was obtained in nine patients, one was cured after additional surgery, and one underwent radiosurgery. Hallucination occurred in one completely cured patient on day one. Based on this experience, we believe that intraarterial Onyx may be the primary treatment of choice for patients with TSDAVFs. The applicability of this new embolic agent indicates the need for reconsideration of the treatment strategy for such fistulas.