Atypical teratoid/rhabdoid tumors (AT/RT) of the central nervous system are rare and extremely aggressive malignancies of early childhood. We report a case of AT/RT in an adult patient. A 30-year-old woman presented with headache, vomiting and ataxia during the second trimester of pregnancy. Magnetic resonance imaging revealed a posterior fossa mass. A gross total resection was performed. Pathological examination revealed an AT/RT. Despite the dismal prognosis the patient decided not to undergo an abortion. For this reason postoperative accelerated hyperfractionated radiotherapy was limited to the tumor region. Six months later the woman delivered a healthy baby. One week postpartum, a central nervous system recurrence localized apart from the primary lesion was treated with radiosurgery. Two months later a diffuse progression was noted. Despite a 6 week course of oral temozolomide, the tumor progressed and the patient died 11 months after diagnosis. Although survival was short, surgery and involved field radiotherapy yielded a progression-free interval of 9 months. This allowed the patient to carry pregnancy to term. Radiosurgery resulted in a complete remission of the first recurrence. Oral chemotherapy was not effective in controlling diffuse tumor spread.