We report on the long-term followup of 7 patients 11 to 50 years old treated for arterial priapism following perineal or penile trauma with arteriographic evidence of contrast medium extravasating from a lacerated cavernous artery into surrounding erectile tissue lacunae (an arterial-lacunar fistula). All patients underwent medical record review and completed a mailed questionnaire. The priapism erections were described as devoid of pain or tenderness, incompletely but constantly rigid and able to increase rigidity with sexual stimulation. Bright red corporeal aspirates were observed in all cases. Color flow Doppler ultrasound findings of focal areas of high flow turbulence correlated with diagnostic arteriography (correlation coefficient 1.00). Initial treatment by mechanical or pharmacological means was unsuccessful when performed. Superselective transcatheter embolization of the ipsilateral common penile artery resolved the priapism in all cases. The interval from onset to resolution of priapism was 4 to 126 days. Full erectile function return was delayed from 2 weeks to 5 months, most likely from resolving clot lysis. Full erection quality was restored in 6 of 7 patients with persistent function and restored frequency of intercourse at 6 to 67 months. Reestablished cavernous artery flow in previously embolized arteries was demonstrated on followup ultrasonography. Surgical treatment was not required in any case. We conclude that arterial priapism occurs in the absence of neurogenic-mediated relaxation, and is sustained by high oxygen tension and shear stress associated with the cavernous artery laceration. Embolization therapy offers effective management of the pathophysiology with high preservation of premorbid erectile function.