The authors present two cases of ureteral valves. This rare urinary tract defect, causing abnormal urine flow from the upper urinary tract, is usually diagnosed intraoperatively. A 15-year-old girl with renal colic was admitted to hospital. Abdominal ultrasonography showed pelvicalyceal dilation in the right kidney and the X-ray showed a shadow in the orifice of the left ureter. She underwent bilateral ureterorenoscopy. A left ureteral valve was visualised during the examination. A 13-year-old boy was admitted to the Department of Surgery due to pelvicalyceal and left ureteral dilatation. Based on imaging and clinical findings, both patients underwent surgical treatment. Valves were found in the distal part of the left ureters. They were resected and the ureters were transplanted. Histopathological examination showed the presence of smooth muscle in the folds of the valve, confirming the final diagnosis.