To determine whether color Doppler ultrasonography (CDUS) would add to the understanding of the bladder wall after endoscopic subureteral collagen injection (SCIN), 25 patients were studied with CDUS. The kidney length and echogenicity, the volume of the collagen, the mean length of the urinary jet, the longitudinal and transverse angles, and the distance between the origin of the jet and the midline of the bladder were measured 1 day, 1 month, and 3 months after SCIN and compared to the results of micturating cystourethrograms (MCUs) performed 3 months after SCIN. The collagen was hyperechogenic compared to the bladder wall at the time of injection, and was isoechogenic 1 and 3 months after SCIN. CDUS showed the relationship between the injected collagen and the position of the ureteral orifice. The measurements of jet length, angle, and distance of the ureteral orifice from the midline did not correlate with vesicoureteral reflux assessed by MCU. Although CDUS may demonstrate the location, the size of the injected collagen implant, and its relationship to the ureteral orifice, it is as yet unable to predict vesicoureteral reflux after SCIN.