To evaluate the efficacy of bladder ultrasound (US) in predicting the resolution of vesicoureteral reflux (VUR) after subureteral endoscopic Deflux injection in low-grade vs high-grade VUR patients. Between 2014 and 2020, 160 children (220 ureters) were administered subureteral Deflux injection for treatment of primary VUR. The mean age at surgery was 72 months. Low-grade reflux (grades II-III) was observed in 190 ureters and high-grade reflux (grades IV-V) was observed in 30 ureters. Bilateral surgery was performed in 60 patients. All patients had follow-up using bladder US and voiding cystourethrography (VCUG) at 3 months and 12 months. Outcome included identification of Deflux mounds by bladder US and correlation of Deflux mounds identified with radiographic success rates of VUR on VCUG. Single Deflux injection showed radiographic success rates in 98% of low grade reflux patients and 26.7% of high grade reflux patients at last follow-up. Bladder US was able to detect Deflux mounds in 89% of low grade reflux and 43.3% of high grade reflux patients at last follow up. Our study demonstrated higher sensitivity, Positive predictive value and accuracy in Deflux detection by bladder US in low grade reflux vs high grade reflux patients. Bladder-US was highly sensitive for detection of Deflux implants. Bladder-US could be adjusted in follow-up of patients with low-grade reflux treated by Deflux injection, while VCUG could be preserved for follow-up of high-grade reflux, this will lead to reduction of unnecessary radiation exposure during VCUG for children with low grade reflux.