Congenital obstruction of the male urethra is usually caused by posterior urethral valves. Anterior urethral valves (AUV) represent a rare anomaly with a wide spectrum of presentation varying from mild voiding difficulties to end-stage renal disease. Prompt diagnosis and appropriate treatment is essential to prevent renal impairment. We report the case of a 13 month-old boy who presented with deterioration of kidney function caused by unrecognized AUV disorder. Temporary cutaneous vesicostomy was necessary to protect the upper urinary tract from further damage and to stabilize renal function. Even though a voiding cystourethrogram (VCUG) demonstrated obstruction of distal urethra, AUV were initially overlooked but finally diagnosed on additional VCUG followed by urethroscopy.