Unilateral absence of the vas deferens is frequently associated with ipsilateral anomalies of the urinary tract. A case of congenital absence of the vas deferens on the right side was associated with retrocaval ureter in a 30-year-old male. He was married and sterile for two years. On scrotal exploration, both testicles were normal but the vas deferens and the body and the tail of the epididymis on the right side were absent. The tail of epididymis on the left side was obstructed. Therefore, we performed a vaso-epididymostomy on the left side and anastomosed an artificial spermatocele on the body of the right-sided epididymis. The diagnosis of retrocaval ureter was confirmed by the intravenous pyelography and the retrograde pyelography.