Purpose: Intraurethral prostaglandin E-2 (PGE(2)) administration is a noninvasive treatment modality for erectile dysfunction. The purpose of this study was to evaluate the objective effects of this agent by measuring peak systolic velocities of cavernosal arteries after intraurethral PGE(2) administration and comparing with the results obtained with an intraurethral placebo gel and intracavernous papaverine injection. Materials and Methods: The study group consisted of 22 consecutive impotent volunteers with a mean age of 46 years who had normal penile arterial responses as determined by penile arterial responses on papaverine-stimulated penile duplex ultrasonography. The peak systolic velocity in cavernosal arteries was recorded after intracavernous injection of 60 mg of papaverine. All patients received 1 mg of intraurethral PGE(2) gel and placebo at 15-day intervals. The peak systolic velocities were recorded after each treatment. Results: Mean peak systolic velocity achieved by intraurethral administration of PGE(2) gel (25 +/- 8 cm/s) was less than that achieved by intracavernous papaverine (40 +/- 6 cm/s) but higher than that obtained by placebo (15 +/- 4 cm/s). Twelve patients had erections, while 9 had partial and 1 had no erection with intraurethral PGE(2)-Placebo did not cause any erections. No serious side effects were observed. Conclusion: Intraurethral administration of PGE(2) appears to be an effective and simple method for increasing penile arterial flow and can be used during penile Doppler ultrasonography to stimulate the penile arterial system. Copyright (C) 2001 S. Karger AG, Basel.