The anatomy of the ureterovesical junction is a point of controversy. It was described as one way valve allow the passage of urine from the ureter to the bladder and prevent its reflux in the opposite direction. In the present study the anatomy of the ureterovesical junction was discussed regarding the orientation and the arrangement of the muscle fibers in the lower end of the ureter, the sheath surrounding the ureter which is known as Waldeyer's sheath and the layers of the trigone. The possible role of the above items in the antireflux mechanisms.