The authors present a case of ectopic opening of the left ureter into the seminal tract. This was a very young child (14 months). The diagnosis was made on intravenous pyelography on direct signs (opacification of the malformation). There was a wide communication between the latter and the posterior urethra as was shown on retrograde urethrocystography. The urinary tracts on the side of the lesion were very fine, and there was an outline of a very mildly functional kidney. Embryologically it is a case of absence of separation between the ureteral bud and the Wolffian canal.