Purpose Collagen has been used for the endoscopic subureteral treatment of vesicoureteral reflux since the late 1980s. We evaluated the long-term efficacy of repeat subureteral glutaraldehyde bovine cross-linked collagen injections for the endoscopic management of vesicoureteral reflux. Materials and Methods We prospectively evaluated 14 girls and 2 boys (21 ureteral units) 6 months to 16 years old (median age 6 years). In all patients initial treatment failed or reflux recurred after a single subureteral collagen injection and injection was repeated. Patients were followed with voiding cystography. Reflux-free periods after each injection and reflux grade were documented. Results All patients were treated twice with subureteral bovine collagen injection. Mean injected collagen volume of injections 1 and 2 was 1.5 ml. (range 0.7 to 3.0) and 1.6 ml. (range 1.0 to 2.3), respectively, at a concentration of 35 mg./ml. In all but 4 cases reflux disappeared after injection 2. Mean followup was 11 months (range 1 to 41) after treatment 2. However in 10 patients (13 ureteral units) treatment failed or reflux recurred a mean of 10 months after injection 2. The reflux-free period after injection 2 was prolonged compared to that after injection 1 (p <0.05). Conclusions Our results suggest that repeat endoscopic subureteral bovine collagen injections prolong the reflux-free period but remain ineffective at long-term followup for correcting vesicoureteral reflux.