Nephroblastoma is an uncommon renal malignancy primarily observed in the pediatric population, with its occurrence in adults being exceedingly infrequent. We describe an extremely rare case of a malignant embryonal tumor presenting in an adult patient with right renal mass. Final histopathologic diagnosis was nephroblastoma with favorable histology. Use of immunohistochemistry studies is generally unnecessary but its rarity in the adult population raises uncertainty in diagnosing this malignancy by histomorphology alone.