The aim of this study was to evaluate associated urological anomalies and renal outcome in children with unilateral renal agenesis (URA). Medical records of 51 cases of URA followed at Şanlıurfa Children 's Hospital between January 2009 and December 2012 were reviewed retrospectively. In all patients, diagnosis was made by abdominal ultrasound (US) and confirmed by a radionuclide scan. The children were between 3 months and 17 years of age (median age: 5 years). There were 31 males (60.8%) and 20 females (39.2%). In 33 patients (67.3%), the left kidney was absent. Urological anomalies were found in 12/51 patients (23.5%), including ureterovesical junction obstruction in 4 (7.8%), bladder dysfunction in 2 (3.9%), and vesicoureteral reflux (VUR), ureteropelvic junction obstruction, ureterovesical and ureteropelvic junction obstruction, duplicated collecting system plus grade IV VUR, ectopic kidney plus grade V VUR, and ectopic kidney in 1 patient (2%) each. Chronic renal insufficiency (CRI) developed in 5/51 patients (9.8%) (stage III in 3 patients and stage IV in 2), 4 of whom had additional urological anomaly; in the remaining 1 patient, a 17-year-old female, imaging studies were normal except for a small and hyperechogenic solitary kidney determined on US. A total of 3 patients (5.8%) developed hypertension, and all except one had an associated urological anomaly. Proteinuria was seen in 2 patients (3.8%) with stage IV CRI, one of whom was also hypertensive. In conclusion, urological anomalies usually accompany URA and should be followed closely to decrease the risk of renal failure.