ABSTRACT Purpose We compared the efficacy of subureteral polydimethylsiloxane injection (Macroplastique, Uroplasty, Inc., Minneapolis, Minnesota) versus open surgery for correction of varying degrees of reflux in complete duplex systems. Materials and Methods Between 1997 and 2000 polydimethylsiloxane injection was performed in 15 females (22 refluxing moieties). Mean patient age at presentation and at surgery was 54 and 94 months, respectively. Extravesical common sheath reimplantation (ECSR) was performed in 34 children (bilateral 10) with a mean age at presentation and at surgery of 31 and 57 months, respectively. Voiding cystourethrography and ultrasound were performed at 3 months. In cases of persistent reflux repeat voiding cystourethrography was performed at followup. We then analyzed the surgical outcome for both groups. Results Mean followup for the injection and ECSR groups was 12 and 15 months, respectively. The success rate per moiety after injection was 68% at 3 months, which increased to 81.8% at 12 months. One patient had contralateral vesicoureteral reflux and none had de novo hydronephrosis, urinary tract infection or complications postoperatively. The success rate of ECSR was 95.5% at 3 months, which improved to 97.7% at an average of 15 months (p <0.04). After ECSR transient contralateral vesicoureteral reflux was seen in 4 renal units, de novo hydronephrosis was seen in 2 units and 4 patients had urinary tract infections. Conclusions Although endoscopic subureteral polydimethylsiloxane injection was simple and successful in more than 80% of patients with low grade vesicoureteral reflux in duplex systems, it is less effective than surgery with regard to elimination of reflux.