We report a case of androgen insensitivity syndrome (AIS) characterized by malignant degeneration of the testes consisting of gonadoblastoma and dysgerminoma. AIS is a rare inherited form of male pseudohermaphroditism that can manifest as a normal female phenotype without müllerian derivatives and absence of the upper third of the vagina. A 32-year-old white 46,XY female with AIS underwent removal of the dysgenetic gonads at the Gynecological Oncology Department of the Istituto Nazionale Tumori, Milan, Italy. We investigated cytogenetic alterations, hormonal levels and the presence of neoplasia in the dysgenetic gonads. Histological analysis revealed a gonadoblastoma mixed with dysgerminoma in the left gonad and a pure dysgerminoma in the right gonad. The patient's hormonal status matched that of a male. Second-look laparotomy after chemotherapy showed a complete pathological response. AIS should be suspected in phenotypically female patients with primary amenorrhea; surgical removal of the gonads is mandatory to avoid malignant degeneration.