Atypical teratoid/rhabdoid tumors (AT/RTs) of the CNS have been recently characterized as a distinct clinicopathologic entity with an unusually poor prognosis and with the highest incidence in the first 2 years of life. It often arises in the posterior fossa and its distinctive immunohistochemical (negative stain for INI-1) and cytogenetic features (monosomy or deletion of chromosome 22) permit an adequate diagnosis in most of cases. AT/RT of the CNS is a usually fatal disease virtually unresponsive to chemotherapy (CT) and radiotherapy (RT). Rapid progression and CNS dissemination are commonly reported. Whether combined regimens including high-dose CT are able to prolong survival or change the natural history of this tumor are under evaluation.