Abstract: Background & Objectives: Urinary tract infections (UTIs) are one of the most frequent diseases which if misdiagnosed can lead to complications such as renal scars. To prevent this complication, it is necessary to identify all the children who are at high risk for renal scars following UTI for treatment and follow them up seriously. The aim of this study was to investigate the probable relationship between factors such as age, sex, fever, microorganism involved, vesicoureteral reflux and its severity and number of recurrence episodes of UTI with occurrence of persistant renal scar in children suffering from UTI. Materials & Methods: This descriptive- analytic study was done on 50 children aged 37 days to 15 years with UTI who referred to Dr. Sheykh Hospital Mashhad-Iran. The study was judgmental non-probability sampling. Urinary tract sonography during the treatment and voiding cystourethrogram (after U/Cs turned out to be negative) were performed in all cases. DMSA scan was done 6 months after diagnosis of UTI to demonstrate renal scar. Results : Renal scars were seen in 22 out of 50 patients. Of the 50 patients, 9 were boys and 41 girls 66% of cases had fever. The etiologic germ was E. coli in 84% of cases and the recurrence pathogen was also E. coli in 71.9% of cases.VUR occurred in 55.6% of patients and dilated reflux (grade III and more) was 44.4%. The mean number of recurrence in patients who developed renal scar was 3.9 and in the others without scar it was 1.93. Finally, the association between the male sex and unusual microorganisms (non E. coli) in recurrence of UTI and relation of VUR, dilated reflux and recurrence episodes with renal Scar was statistically confirmed (P<0.05). Conclusion : According to our data from this study, the risk factors for renal scar followed by UTI are male sex, non E coli pathogens, VUR, VUR grade III and higher and the number of UTI recurrences.