Abstract: This study aimed at evaluating the sacrum index in children suffering from different grades of vesicoureteral reflux. In this case-control study, according to VCUG results, children with grade III, IV and V refluxes entered the study. There were 76 children with history of urinary canal infection and normal VCUG. Sacrum index was measured in both groups and compared. There was a meaningful relationship between these two groups considering abnormality rate of the index (p = 0.001). The factor can be used as a predictive factor in determining prognosis of medical treatment and selecting those children candidate to surgery.