A 51-year-old man presented at our department 2 days after the onset of a painful mass in the perineum and dysuria. Diagnosis of partial priapism secondary to proximal segmental corpora cavernosa thrombosis was made through colordoppler ultrasound (CDU) and magnetic resonance imaging (MRI). Treatment consisted of administration of systemic anticoagulation drugs (acenocumarol) and local injection of ethylephrine chloridrate. The thrombosis resolved after two months with incomplete restoration of erectile function (loss of rigidity). In conclusion, on the basis of previous reports (23 cases reported in literature) and our experience, in presence of painful mass in the perineum, CDU and MRI evaluation allows to make diagnosis of the rare proximal partial priapism that as first option should be treated conservatively.