A case of huge primary leiomyoma of the ureter in which nephroureterectomy was performed is presented. To the best of our knowledge, this case is a unique form of leiomyoma of the ureter due to its large size. There have been only twelve cases of primary leiomyoma of the ureter reported since 1955 and eleven of them were very small and one was big in size but smaller than the present case. Our case is considered to be the thirteenth.