A 33 year-old woman suffered from intermittent urinary incontinence since her teen age, the incontinence exacerbated after delivery of two children. Physical examination revealed a type 4 genuine stress incontinence and endoscopic bladder neck suspension was undertaken. However, after operation, persistent urine leakage was noted when large amount of intravenous fluid was given. Further examination and probing found an ectopic ureteral orifice existing in the vaginal vestibule. Retrograde catheterization and pyelopgraphy revealed the ectopic ureter drained a small upper segment of the left kidney. A second surgery was carried out to anastomose ectopic ureter to the normal ureter and the left kidney. A second surgery was carried out to anastomose ectopic ureter to the normal ureter and the patient regained her continence after operation. For patients with urinary incontinence, coexistence of ectopic ureter and genuine stress incontinence is possible. The lesson of this unusual case teaches us detailed physical examination and interpretation of urography is necessary in order to rule out other possibility of urinary incontinence although a frank diagnosis has presented.