Swyer syndrome – or pure gonadal dysgenesis – is one of the type of gonadal dysgenesis. The affected person suffers from primary amenorrhea, does not develop secondary sex characteristics. Seventeen-year-old girl was admitted due to right ovarian tumors of small cell carcinoma. Dysgerminoma shares several clinical and pathologic entities with small cell carcinoma. We reported a case of dysgerminoma in Swyer syndrome with pathologic ambiguity.