PURPOSE: The aim of this study was to review the experience of a single institution with the endoscopic Deflux (Q-Med Scandinavia, Uppsala, Sweden) procedure and assess its effectiveness in the treatment of refluxing duplex systems. MATERIALS AND METHODS: A retrospective review of all patients that underwent endoscopic Deflux treatment for vesicoureteral reflux (VUR) in duplex systems between June 2003 and July 2007 was performed. Data collection included: age, gender, side of refluxing ureter, preoperative radiologic grade of VUR on a voiding cystourethrogram (VCUG), presence of VUR on a radionuclide VCUG 3 months postprocedure, volume of Deflux injected, number of Deflux injections performed per patient, and number of patients that underwent reimplantation surgery. RESULTS: Sixteen patients with duplex systems, two being bilateral, for a total of 18 duplex ureteral systems, underwent the Deflux procedure. Grades of reflux were as follows: grade II: 4 ureters; grade III: 8 ureters; grade IV: 4 ureters; and grade V: 2 ureters. Deflux injection volume ranged from 0.28 to 1.5 cc (mean, 0.84). Fourteen ureteral systems required one injection, three required two injections, and one required three injections. The overall success rate of the procedure after a maximum of three injections was 94%. One patient with preoperative unilateral grade V reflux had persistent high-grade reflux after two injections and opted to proceed with surgical reimplantation. The mean follow-up was 24 months (mean, 6-48). CONCLUSIONS: We conclude that the Deflux procedure is a safe, effective minimally invasive treatment alternative for patients with refluxing duplex systems.