PURPOSE: Vesicoureteral reflux is a risk factor for progressive renal damage associated with urinary tract infection. Mild to moderate reflux is routinely treated with long-term antibiotic prophylaxis to prevent recurrent infections and open surgical reimplantation for breakthrough infections despite antibiotic therapy. Endoscopic subureteral injection of implant material is a therapeutic alternative to long-term prophylaxis and open surgery but its widespread use in the United States has been prevented by the lack of a stable implant material. Dextranomer/hyaluronic acid copolymer has been shown to be a safe, effective and durable implant material and was recently approved in the United States. We estimate the effect on costs and cure rates of introducing endoscopic injection with dextranomer/hyaluronic acid copolymer as a treatment alternative in the United States. MATERIALS AND METHODS: We constructed a model that mimics current clinical practice of vesicoureteral reflux treatment for 6 years, and incorporates spontaneous resolution and surgical intervention rates obtained from 2 long-term followup studies. The treatment algorithm was established using medical data from the literature, and clinical management practices from a Delphi survey of 27 pediatric urologists and nephrologists across the United States. Endoscopic injection was introduced into the model as replacement to surgery or alternative to long-term antibiotic prophylaxis. The effectiveness of dextranomer/hyaluronic acid copolymer was calculated from 140 patients (208 ureters) with grade III reflux treated in a clinical study of 221 children in Sweden. RESULTS: With current practice, the average cost per patient in 6 years was 6,640 US dollars and 23.5% of patients continued to have reflux. Replacing open surgery with endoscopic injection led to similar cure rates (22.2% failures) but costs were reduced to 5,522 US dollars. When injection was performed after 1 year of antibiotic therapy failure rates were reduced to 8.5% but costs increased to 7,644 US dollars. CONCLUSIONS: Our results show that a persistent approach to endoscopic surgery can be expected to result in overall success that equals or exceeds open surgery at a lower cost. This finding is particularly true if open reimplant is reserved for patients with high grade or persistent vesicoureteral reflux.