Priapism, that is a long lasting erection in absence of sexual desire and is sometimes painful, has represented a rare occurrence until few years ago; such occurrence has become much frequent since pharmaco-erection have been used. There are still many doubts about the etiopathogenesis of priapism, that anyway happens because of a long lasting pathological discrepancy between arterious flux to penis corpora cavernosa and venous down flowing. For to establish how and when we must treat priapism, it is very important to know the causes of it, so that we can use the more properly therapy for each case. It's possible to classify the therapies in the following ways: a) extracavernosa, b) located in the corpus cavernosum. These last ones are most used and include the punction and the drainage of the blood of the cavernous body and sometime the "shunt" spongio-cavernosum. The treatment must be effected without loss of time in those rare cases of spontaneous priapism. Indeed, according to our experience, it's not necessary to be extremely supporting for intervention for priapism post pharmaco-erection. In fact the wait of 8-10 hours reduces the number of invasive treatments, without danger for the integrity of cavernous tissue.