One case of congenital renal cyst with agenesia of the left ureter and parts from it originated has been described by the authors. The contents of the cyst was about 800 ml of red-brown fluid. By macroscopic examination, it was impossible to discern the renal pelvis. By microscopic examination, it was not found any structure like the parenchyma of the kidney. After referring the cases recorded in the available literature, they have concluded this case in not so common.