We report on an infant with unilateral renal lymphangiectasia and the absence of small cysts in the renal parenchyma or renal hilum. We suggest that renal lymphangiectasia be part of the differential diagnosis in children who present with unilateral renal enlargement, especially when contrast enhanced computerized tomography shows preservation of a rim of renal cortex with decreased attenuation of the medulla and/or when ultrasound demonstrates increased echogenicity without displacement of the caliceal system.