Congenital Unilateral Renal Agenesis is defined as the complete absence of one kidney due to failure of the wolffian duct to give off a corresponding ureteric bud, and have not to be ocnfused with renal hypoplasia, aplasia, chronic atrophy, or fusion anomaly. Usually this condition has no clinical symptom and is discorved during a routine urographic study for some other genitourinary diseases. So the reported cases are uncommon but not rare in autopsy series. This situation occurs more on the left side, and more in males. We have experienced 2 cases of Congenital Unilateral Renal Agenesis proved by Radiologically and Surgically, and report with brief review of the literatures.