To establish if interruption of the intradural draining spinal vein or surgical excision are curative treatments for spinal dural arteriovenous fistulas (AVFs), the medical records and radiographic studies of 19 patients with spinal dural AVFs and progressive myelopathy were reviewed. Spinal arteriograms were obtained before and within 2 weeks after surgery in 19 patients, and after a delay of 4 months or more in 11 patients. The mean clinical and arteriographic follow up was at 37 and 35 months, respectively. In the 11 patients who underwent excision of the dural AVF there was no evidence of a residual lesion upon immediate or delayed postoperative arteriography. Surgery in eight patients consisted of simple interruption of the intradural draining vein as it entered the subarachnoid space. In six of these patients the vein draining the AVF intrathecally provided the only venous drainage of the AVF. In these six patients there was no immediate (six of six) or delayed (four of six) arteriographic evidence of residual or recurrent flow through the AVF. Two patients had an AVF with both intra- and extradural venous drainage; after intradural division of the draining vein there was residual flow through the AVF into the extradural venous system. In one of these two patients intrathecal venous drainage was reestablished, which required additional therapy. In the other patient the extradural AVF spontaneously thrombosed and was not evident on delayed follow-up arteriography. In patients with spinal dural AVFs with only intrathecal medullary venous drainage, which includes most patients with these lesions, surgical interruption of the intradural draining vein provides lasting and curative treatment. In patients with both intra- and extradural drainage of the AVF, complete excision of the fistula or interruption of the intra- and extradural venous drainage of the fistula is indicated. In patients in whom a common vessel supplies the spinal cord and the dural AVF, simple surgical interruption of the vein draining the AVF is the treatment of choice, as it provides lasting obliteration of the fistula and it is the only treatment that does not risk arterial occlusion and cord infarction. Simple interruption of the venous drainage of a spinal dural AVF provides lasting occlusion of the fistula, as it does for cranial dural AVFs, if all pathways of venous drainage are interrupted. This result provides further evidence that the venous approach to the treatment of dural AVFs can be used successfully.