To review the symptoms and progression of dural arteriovenous fistulas (AVFs) and correlate the findings with various angiographic patterns. Patterns of venous drainage allowed classification of dural AVFs into five types: type I, located in the main sinus, with antegrade flow; type II, in the main sinus, with reflux into the sinus (IIa), cortical veins (IIb), or both (IIa + b); type III, with direct cortical venous drainage without venous ectasia; type IV, with direct cortical venous drainage with venous ectasia; and type V, with spinal venous drainage. Type I dural AVFs had a benign course. In type II, reflux into the sinus induced intracranial hypertension in 20% of cases, and reflux into cortical veins induced hemorrhage in 10%. Hemorrhage was present in 40% of cases of type III dural AVFs and 65% of type IV. Type V produced progressive myelopathy in 50% of cases. This classification provides useful data for determination of the risk with each dural AVF and enables decision-making about the appropriate therapy.