We report an unusual case of a ureterocele in a duplex system, which was associated with an ectopic (vulval) upper moiety ureter. This is the second case reported in the literature of a ureterocele arising from the lower pole ureter. Surgical treatment consisted of removal of the upper segment of the kidney and its ureter. The ureterocele was excised and the lower pole ureter was reimplanted in the bladder. At followup 14 years postoperatively the patient was cured and free of urinary infection.