ABSTRACT Swyer syndrome is a pure gonad dysgenesis associating with 46.XY karyotype, primary amenorrhea and presence of female internal genital tract and bilateral streak gonads in a phenotypic female. The diagnosis is usually made at adolescence when the primary amenorrhea is investigated. A 23-year-old female presented with primary amenorrhea. On physical examination, she had female external genitalia. Laboratory analyses revealed serum follicle-stimulating hormone and luteinizing hormone levels compatible with hypergonodotropic hypogonadism. Pelvic ultrasonography and magnetic resonance imaging showed a hypoplastic uterus and absent ovaries. Chromosome analysis revealed 46.XY karyotype. Prophylactic bilateral gonadectomy was performed and histological examination showed pure gonadoblastome in the left ovary. In conclusion, the presence of Y chromosome in patients with 46.XY gonadal dysgenesis may increase the risk of gonadal tumors. A prophylactic bilateral salpingo-gonadenectomy should be advised to those patients.