The transabdominal suprapubic study of the seminal vesicles was realised in 162 cases. Their relationship with the posterior bladder wall was examined. The normal distance between distal extremity of seminal vesicles-bladder wall measures 5 mm, and the distance between proximal extremity of seminal vesicles-bladder wall measures 7 mm. In case of benign hypertrophy, the seminal vesicles are pressed back and distance proximal extremity of seminal vesicles-bladder wall gets greater than 15 mm. In malignant hypertrophy of the posterior prostatic lobe, the position of the seminal vesicles does not change although the prostate has an increased volume.