Abnormalities of wolffian duct derivatives are usually encountered in young subjects. We identified 4 instances of embryologic malformations of these structures in patients who underwent radical prostatectomy (RP). The first patient had unilateral renal agenesis and a seminal vesicle cyst identified preoperatively by computed tomography. The seminal vesicle cyst was removed during RP. The second patient had renal agenesis and an ectopic ureter entering the right seminal vesicle. These were treated with ureterectomy during RP. The third patient had unilateral duplication of the vas deferens of no clinical consequence. Finally, the fourth patient had left-sided absence of both the vas deferens and seminal vesicle. The anatomy of the lower pelvis is most accurately shown on magnetic resonance imaging. Lower urinary tract malformations are an uncommon occurrence in males. Surgeons who perform numerous RPs will, however, find additional urologic pathologies during RP that may require consideration and tailored management.