Spinal dural arteriovenous fistulas are the most common type of arteriovenous malformation involving the spinal cord, especially in middle-aged men. We report 21 patients with this malformation who had signs and symptoms of myelopathy. The diagnosis was established by selective spinal angiography in patients whose neurological deficits, myelograms or magnetic resonance tomographies suggested the presence of a spinal arteriovenous fistula. They were treated by microsurgical coagulation of the fistula nidus located in the dura and intradural division of the draining vein. Twenty patients improved neurologically following surgery, one remained unchanged. Complete obliteration of all lesions was verified by intra-operative microvascular Doppler sonography and in 3 cases by postoperative angiography. There were only a few minor and transient complications after surgery: one neurological deterioration where venous thrombosis was suspected, one cerebrospinal fluid accumulation and, in one case a transient wound healing impairment. Two patients had to be operated on again. In one case with difficult localization of a fistula at the L5/S1 level, the fistula was still visible in the postoperative angiogram. In another patient, a spinal epidural haematoma occurred a few hours after surgery. We conclude that microsurgical treatment of spinal dural arteriovenous fistulas is a safe, fast, simple and effective method of treating these lesions. However, recovery after surgical management was often incomplete because the diagnosis was established too late and the patient already presented with severe and long-lasting deficit. Thus, the main problem remains a diagnostic and not a surgical one.