Sixty-one patients affected by de Lange syndrome underwent a careful renal and urological evaluation including family and personal history, physical examination, urinalysis, renal tract ultrasonography, and serum creatinine. A voiding cystourethrography was performed in patients with urinary tract infections, in patients with renal ectopy, and in patients with small kidneys. Structural anomalies of the kidney and urinary tract were detected either by ultrasound or voiding cystourethrography in 25 patients (41%): absent or poor corticomedullary differentiation (N = 8; 13%), pelvic dilation (N = 6; 10%), vesicoureteral reflux (N = 5; 8%), small kidney (N = 3; 5%), isolated renal cyst (N = 3; 5%), and renal ectopia (N = 2; 3%). Renal function was normal in 52 patients (85%) but reduced in 9 patients (15%) with renal tract abnormalities. Overt proteinuria was disclosed in three patients with impaired renal function. © 2005 Wiley-Liss, Inc.