Keskin M, Savaş-Erdeve Ş, Kurnaz E, Çetinkaya S, Karaman A, Apaydın S, Aycan Z. Gonadoblastoma in a patient with 46, XY complete gonadal dysgenesis. Turk J Pediatr 2016; 58: 538-540.46, XY complete gonadal dysgenesis (Swyer syndrome) is a rare cause of 46, XY sexual development disorder. The patient presented to our clinic with absence of breast development and lack of periods at the age of 17 years. Her history and familial history involved no relevant conditions. She had Tanner stage 1 thelarche, and Tanner stage 2 pubic hair development with no axillary hair development. External genital structure appearance was consistent with female phenotype and the patient had no palpable gonad. The patient diagnosed as 46, XY complete gonadal dysgenesis after evaluation of laboratory analyses, radiological methods and karyotype. The Sexual Orientation and Gender Identity Committee concluded that gonadectomy should be performed. Histopathologic analysis demonstrated gonadoblastoma. Gonad structures should be sought laparoscopically and once diagnosed, streak gonads should be removed prophylactically in patients with 46, XY complete gonadal dysgenesis.