Vesicoureteral reflux (VUR) is reported in 30%-50% of children affected by urinary tract infection (UTI). We aimed to investigate the frequency of VUR in children presenting with UTI and the changes in its prevalence from birth up to 18 years. This research was an observational retrospective study in the nephrology clinic of an academic tertiary hospital during 2003-2016. Patients with UTI subjected to direct cystourethrography were enrolled (908 patients, 86.23% of girls and 13.77% of boys). They were aged from 3 days to 214 months (33 ± 33.2 months). VUR was observed in 419 of 908 (46.14%) cases. High-grade VUR (VUR Grades IV-V) and VUR were significantly more prevalent in boys (P = 0.001 for both). Only 9.2% of the VUR subjects were diagnosed after 5 years of age. The patients with VUR developed UTI at a significantly younger age compared with those without VUR (P = 0.0001). Abnormal kidney ultrasound results were significantly more common in patients with VUR than in those without VUR (P = 0.0001). The prevalence of VUR in the 1 st , 2 nd , 3 rd , 4 th , and 5 th years of life was estimated to be 56.64%, 48.2%, 49.46%, 35.8%, and 45.07%, respectively. The highest and lowest VUR prevalence was 56.64% (1 st year of life) and 0% (13-18 years). In addition, severe VUR was not an uncommon finding, and affected 10.7% of the total population. The results indicated a decrease in the prevalence of VUR with increased age when considering the five main age subgroups of childhood.