This report presents the fine-needle aspiration cytology (FNAC) findings of a multicystic renal tumor found in a 3-year-old child. The smears contained benign epithelial cells isolated or arranged in sheets of uniform cells strongly suggesting the lining of the cysts. The combination of the imaging data with the FNAC findings favoured the diagnosis of cystic nephroma (CN), a benign renal tumor that is cured by surgery. Surgical pathology confirmed the diagnosis. CN should be added to the list of tumors of the kidney in infancy that appear to be diagnosable by FNAC/biopsy.