: Two-month-old female presented with left loin swelling and pain. The swelling was 8cmx6cm and it was ballotable in nature. It was gradually increasing in size.: To find out the incidence of this rare, high index of suspicion, investigations including cytopathology and histopathology, early diagnosis and management.: The informed consent from the parents of the patient was taken. The study was carried out in a tertiary care hospital in Kolkata. On CT a heterogenous renal mass was detected. Fine Needle Aspiration cytology from the mass showed mature neural elements, squamous epithelium, mature fat cells a few atypical oval to spindle shaped cells. Cytologically diagnosed as mature teratoma. The tumor was excised. Histopathological examination revealed the diagnosis of immature teratoma. : Immature teratoma is one of the rare causes of Pediatric Kidney Tumor.Renal teratoma is an extremely uncommon tumor in infancy. But it is one of the differential diagnoses of renal mass in infants. Diagnosis may be suspected from radiological investigation and confirmed by histopathological examination. A good prognosis can be expected after proper management.