Endoscopic subureteral collagen injection has become widely accepted a practiced method for the treatment of vesico-ureteral reflux in children. The aim of this study was to evaluate the efficacy of the treatment in adult patients affected by vesico-ureteral reflux. We have selected 45 patients with primary e 10 patients with secondary reflux (tot. 76 ureters) treated by endoscopic subureteric injection of collagen. The success rate after one injection in primary reflux was 74%. 13 ureters required a 2nd or 3rd injection to achieves success. The minimum follow-up time for the successfully treated patients was 12 months; we did not observe no reflux in 92% of ureters. Endoscopic injection of collagen is a reliable alternative to open surgery.