A transvenous embolization technique in which normal cerebral venous drainage can be spared is described. Of 26 dural carotid--cavernous fistulas treated by the authors, the affected cavernous sinus received not only the shunted flow but also the sylvian venous drainage in three cases. Two patients presented with an abducent nerve palsy, and one with an oculomotor nerve palsy. Selective transvenous embolization of the fistulous portions of the affected cavernous sinus was achieved, with preservation of the sylvian venous outflow. Postembolization angiograms revealed complete occlusion of the fistula in one patient and only a small amount of residual shunt in the other two. One of these two underwent subsequent transarterial embolization, and the other was followed without additional treatment. The patients' symptoms resolved between 1 and 2 months posttreatment. Follow-up angiograms revealed that the remnant shunt had disappeared and the sylvian venous pathway had been preserved. The authors conclude that selective transvenous embolization of fistulous compartments in an affected sinus can be used to treat dural arteriovenous fistulas involving a cavernous sinus that also receives the sylvian venous outflow.