A 48-year-old man, who previously had normal erectile function, visited our hospital complaining of a painless erection that had persisted for 6 days. He had suffered perineal trauma in a traffic accident 9 days earlier. A diagnosis of post-traumatic high-flow priapism was suggested from the findings on penile blood gas analysis. Selective internal pudendal arteriography showed an arterial blush along the bilateral cavernous arteries. Subsequently, embolization of a cavernous fistula was performed with an autologous clot. However, the embolus was removed within a minute, so the procedure was repeated with Gelfoam. This patient had normal erectile function after 11 months, with no recurrence of priapism.