Cystic partially differentiated nephroblastoma (CPDN) is a rare neoplastic disorder consisting of a well-demarcated cystic lesion of the kidney where blastemal or other embryonic cells are present in the septa of the cysts. Magnetic resonance imaging can detect the cystic character of the lesion and will produce imaging features that are highly suggestive of either CPDN or cystic nephroma (CN) (synonym: multilocular cyst of the kidney), a benign entity. Although malignant potential exists in CPDN, all cases reported to date have had a favorable prognosis after surgery alone. Partial nephrectomy is considered safe, and the treatment of choice in the newborn period. We report a case of CPDN in a newborn that was successfully treated with partial nephrectomy. More than five years after nephron sparing surgery, the involved kidney shows normal anatomical structure except for a diminished upper pole, no evidence of tumor recurrence and good renal function.