The comparative paucity of reports of cases in which there is a supernumerary ureter, together with the great relief afforded the patient after proper diagnosis and correction, makes a brief review of the subject of interest. As this is a developmental defect, a thorough understanding of the subject requires a review of the embryology. The ureter is formed from the lower part of the wolffian duct. Its distal end divides, to become implanted into the kidney protoplasm. Later the proximal end or end opening into the wolffian duct draws away, and opens separately into the sinus urogenitalis. The important theories advanced to explain bifurcated and double ureter are: Sappey: The ureteral anlage, instead of branching near the kidney, branches sooner, thus forming a bifurcated ureter. Caudmont: The condition is brought about by the partial fusing together of two kidneys. Deubierre: There is a double evagination from the wolffian duct. Any