A male Chinese infant presented with the incidental finding of a left loin mass. Plain abdominal radiograph showed a large left-sided soft tissue shadow. Ultrasound and computed tomography scans demonstrated a multiloculated cystic lesion arising from the upper pole of the left kidney. Histological examination of the nephrectomy specimen confirmed the diagnosis of multilocular cystic nephroma. The differential diagnoses of infantile renal masses, the role of imaging in assessment of these masses and the surgical management of multilocular cystic nephroma are discussed.