Prolonged erection is a rare problem in urology but it must be treated effectively. The most common etiological factor is intracavernosal vasoactive agent injection for diagnosis or treatment of erectile dysfunction, The aim of this study was to evaluate the efficacy of intracavernosal adrenalin injection alone in the treatment of priapism. Nineteen patients with prolonged erection were evaluated. Seventeen out of the 19 prolonged erections were due to intracavernosal vasoactive agent injection and the remaining two were idiopathic. In all cases 2 ml adrenalin (1/100 000) was injected in each cavernosal body. In the patients who did not respond to the first injection, repeated adrenalin injections were performed at 20 min intervals. Blood pressure and heart rate were monitored during the injections. Detumescence was achieved in ten (53%) patients after the first injection. Repeated adrenalin injections (2-5 injections) were required in nine patients and eight (42%) of them achieved detumescence, Only one (5%) patient who had 26-h prolonged erection could not achieve detumescence. There was no significant difference in blood pressure and heart rate during the monitoring of the patients when compared to the initial values. No standard treatment method has yet been described for prolonged erection, Repeated aspirations and irrigations for treatment of prolonged erection are problematical applications both for patients and urologist. Intracavernosal adrenalin injection alone can be used with high efficacy and safety for the treatment of prolonged erection especially in patients with a short duration of erection.