Background: High-flow priapism is a rare condition characterized by a prolonged and painless erection. Since it may permanently impair erectile function, it must be managed and treated as soon as possible, in order to restore potency. The case we are presenting here was successfully treated by embolizing the penile artery using an autologous clot. Case Report: A case of delayed painless high-flow priapism that occured after blunt straddle-type perineal trauma, that was persistent for more than 30 days is being presented. Doppler ultrasonographic examination of the cavernosal artery revealed a 1.5 cm-diameter pseudoaneurysm at the right cavernosal artery, together with a high-velocity shunt between the two cavernous arteries. Extravasation from the proximal sites of both of the cavernous arteries and a right cavernosal artery pseudoaneurysm was detected on angiography. The patient was successfully treated by embolization of the penile artery with an autologous clot in two sessions with a 3-day interval. Conclusions: This experience along with a survey of the literature made us conclude that embolization of cavernous artery by means of an autologous clot is a very effective procedure and a method of choice for treatment of high-flow priapism and for restoration of penile erectile function. What makes our case even more interesting and important, is the fact that priapism of one month's duration could well be treated by means of this method.