Three-dimensional magnetic resonance venography (3D MRV) of the prostate and the pelvic cavity was demonstrated in 8 normal subjects and 12 patients with prostatodynia. In all normal subjects and patients, 3D MRV images were successfully obtained. The deep dorsal vein of the penis sends major branches into the anterior and lateral capsular veins as well as into the internal pudendal vein. In patients with prostatodynia, the anterior and lateral capsular veins were much thicker in diameter than those in normal subjects, suggesting venous congestion. This congestion was also remarkable in the venous plexuses behind the bladder or along the lateral side of the pelvis in patients with prostatodynia. Another characteristic sign of the disease was a narrowing or an interruption of the internal pudendal vein. Prostatodynia is postulated to be caused by intrapelvic venous congestion.