PURPOSE: We aimed to investigate the correlation between serum cystatin C and clinical manifestations in pediatric patients with urinary tract infections (UTIs). METHODS: We studied 137 patients admitted with UTIs from June 2012 to May 2014. Depending on the presence of renal cortical defects on 99m Tc-dimercaptosuccinic acid scintigraphy, we classified patients into non-renal and renal defect groups. Laboratory and clinical parameters were analyzed, including the levels of serum cystatin C. The correlation between cystatin C and other variables was assessed. RESULTS: Serum cystatin C levels did not differ between the non-renal and renal defect groups. In both groups, serum cystatin C levels increased after 4-5 days of treatment, compared with the level at admission (P<0.001). However, mean levels were within normal ranges. The concentration of serum cystatin C positively correlated with serum creatinine and negatively correlated with age (P<0.05). In contrast, there was no correlation between serum cystatin C and other variables. CONCLUSION: Serum cystatin C does not appear to be a useful biomarker for renal defects in pediatric patients with UTIs. Further studies are necessary to conclude whether serum cystatin C is helpful in predicting deterioration in renal function in pediatric patients with UTIs.