The rhabdoid tumor of kindey (RTK) is a neoplasia with well defined clinical and pathological characteristics. Itis is very important to distinguish it form the Wilms'tumor, because RTK is a very aggressive and has poor prognosis. The first case of a RTK diagnsed in Paraguay is presented.The diagnosis was made in a children of 2 years and 11 months of age, presenting a fast and fatal evolution, by immunohistochemical and electron microscopy procedures. Electron microscopy studies demonstrated aggregate of intermediante filaments in the perinuclear area. Immunological studies gave positiy results for vimetin, and negative for desmin and myoglobin