We report a case in which MRA made it possible to diagnose a dural arteriovenous fistula and thrombophlebitis in a 23-year old woman. 2D TOF MRA is the usual technique in the diagnosis of thrombophlebitis. Our experience shows the limits of 2D TOF since the increased signal intensity in the sinus could simulate a normal flow, and we describe the advantages of MR subtraction angiography. In our study, 3D TOF MRA showed the dural arteriovenous fistula, its location near the right transverse sinus and some of the feeding vessels: tentorial branch of the internal carotid artery and meningeal branch of the right occipital artery. 3D TOF MRA provides the diagnosis of dural arteriovenous fistula, but it cannot replace the plain angiography performed before endovascular or surgical treatment.