Rhabdoid tumors represent an independent entity among embryonal neoplasms. These tumors affect the kidney (RTK, rhabdoid tumor of kidney) and central nervous system (AT/RT, atypical teratoid, rhabdoid tumor), but may also be found in peripheral soft tissue. Unifying features include immunohistochemical characteristics and inactivation of the putative tumor suppressor gene SMARCB1 (hSNF5/INI1) in chromosome 22q11.2. Several familial cases have been published and summarized under the term rhabdoid tumor predisposition syndrome. In all of the published familial cases, inactivation of SMARCB1 was detected in tumor tissues.