Retroiliac ureter is a rare congenital anomaly. In this paper, we present a case in which retroiliac double ureters were incidentally found during a retroperitoneoscopic nephroureterectomy procedure in a 5-year-old boy with dysplastic right kidney in duplex system and ureterocele. Ureters were both in the retroiliac artery position. The nephroureterectomy procedure was completed retroperitoneoscopically. After a literature review, this case appeared to be the first report of retroiliac double ureters in a duplex system. © Mary Ann Liebert, Inc.