Introduction: Low success rate for high grade reflux and anatomical abnormality of ureteric orifices continues to be the most important dilemma of the endoscopic treatment of vesicoureteral reflux (VUR). The aim of this study was to evaluate the efficacy of endoscopic polydimethylsiloxane injection in adults with VUR concerning reflux severity and the status of the ureteric orifice. Materials and Methods: Fifty-three ureters (34 patients) were treated with endoscopic polydimethylsiloxane injection. The grade of VUR was I, II, III, IV and V in 2, 13, 25, 10 and 3 ureters, respectively. Any endoscopic characteristics of 'golf hole', broad appearance or lateral placement of ureteric orifices were classified as complex appearance ureters (CAU). Patients with persistent reflux were considered for second and third injections with the same material. Success was determined as no reflux. Results: The total success rate was 100, 92.30, 92, 80 and 66.66% for grade I, II, III, IV and V reflux after the third injection, respectively. The cure rates of ureters with normal appearance were 100, 88.88, 90, 100 and 100% for grade I, II, III, IV and V reflux. The cure rates of CAU were 100% for both grade II and III, 60% for grade IV and 50% for grade V reflux. The injected volumes per renal unit ranged between 0.2 and 3.2 ml (mean 1.05 ml). Conclusions: Although there are disadvantages in the usage of higher volumes of injectable material for successful results and difficulty in subureteral injection both in high grade reflux and complex anatomical situations in adults when compared to children, our results indicate that endoscopic treatment of VUR is an effective therapy for adults. Copyright (C) 2008 S. Karger AG, Basel.