We report on a 23 year old patient with high flow priapism following blunt perineal trauma in which arterial-cavernosal fistula was missed by penile Doppler ultrasonography but was successfully localized by arteriography and embolized using Gelfoam pledgets. Detumescence was complete in 2 days and sexual function returned to the premorbid state after 4 weeks. The diagnosis, pathophysiology, and treatment of high flow priapism and review of the literature are discussed.