The A. describes a case of mixed tumor of the kidney in a 58-year-old male individual. The disease underwent a slow evolution, only being suspected when it attained its final stage. The post mortem examination revealed the presence of a bulky tumor of the right kidney, of a bosselated surface, measuring 19 x 10 x 10 cms. and 940 grs. in weigtht. The tumoral mass destroys the whole kidney structure, of which but very little of recognizable tissue is left. Outside the kidney, blastomatous tissue is also met with in the liver, mesenteric lymphatic glands, peritoneum and apiploon. The tumor structura observed on histological section, varies in conformity with the tissue examined: hipernephroma in the kidney; myoblastic sarcoma in the liver, lymphatic glands, nodules of the peritoneum and epiploon; in some mesenteric glands, apart from the myoblasto-sarcomatous structure, there is nephrogenic tissue, represented by infrequent formations made up epithelial tubules reproducing the structure of uriniferous tubules. Cases of such a feature have been reported as being of particular rarity, and the case here studied approaches very much that described by CHEVREL-BODIN and MARUELLE.