Malignant rhabdoid tumor of the kidney is an uncommon renal tumor in children. The tumor has aggressive behavior and a poor prognosis and is extremely rare in adults; only 3 cases of renal rhabdoid tumors have been reported in adults. We describe here the microscopic, immunohistochemical, and electron microscopic characteristics of another case in a 38-year-old woman. This case reinforces the importance of recognizing this entity in the adult population.