Aim: The purpose of this study was to evaluate prospectively the age-related incidence and severity of primary vesicoureteral reflux (VUR) in siblings of children with reflux and to conclude whether screening of this group is required or not. Methods: A total of 71 siblings (32 boys, 39 girls) of reflux patients, aged less than 15 years (mean age, 8.4 years) were included in the study. Examination methods including urinalysis, urine culture, renal ultrasonography, and voiding cystourethrography were performed in all of the siblings. Additionally, 99m technetium (Tc)-dimercaptosuccinic acid (DMSA) renal cortical scintigraphy was performed in siblings with VUR. Results: Primary VUR was found in 10 (14%) of the siblings, and the incidence for girls and boys were 41.7% and 9.3%, respectively. The reflux incidence in siblings aged less than 6 years was 40%, whereas in siblings older than 6 years it was found 60%. DMSA scintigraphy was performed on all the siblings with VUR, of whom 5 had normal and 5 had abnormal findings. Conclusion: The incidence of primary VUR in siblings of affected children was found higher compared to the siblings of children without the disease, supporting the necessity to screen this population.