Four cases of congenital seminal vesicle anomalies were evaluated using computed tomography. Abnormalities ranged from complete absence of the seminal vesicle to solid and cystic enlargement. Three cases had ipsilateral renal agenesis. Seminal vesicle lesions are uncommon, but may be detected more commonly in the future with increased use of computed tomography, and should be considered when evaluating males with pelvic masses.