['The long-term results of endoscopic trigonoplasty in patients with vesicoureteral reflux were investigated.', 'We performed endoscopic trigonoplasty in 28 patients with vesicoureteral reflux, including 6 girls 6 to 8 years old. Reflux was grade I in 14 reno-ureteral units, grade II in 15, grade III in 8, grade IV in 1 and grade V in 1. Median followup was 23 months.', 'At a median of 3 months postoperatively vesicoureteral reflux was not apparent in 37 units (95%) and it was downgraded in 1 (3%). At a median of 12 months postoperatively 27 (79%) and 4 (12%) of the 34 ureters had cessation and downgrading, respectively. Of the 13 select patients who underwent cystoscopy 3 had retreating ureteral orifices and 5 had trigonal splitting 6 to 12 months postoperatively. Vesicoureteral reflux was demonstrated in 3 of the 5 patients (4 ureters) with trigonal splitting and in 1 (1 ureter) with retreating ureteral orifices. At a median of 24 months after surgery voiding cystography showed reflux in only 1 of 15 units. No postoperative upper urinary tract dilatation was noted at followup.'] Is trigonal splitting a major complication of endoscopic trigonoplasty at 1-year followup?