Paratubal serous borderline tumors are identified mild epithelial atypia and proliferation without stromal invasion. Fallopian tubal or paratubal borderline tumors are extremely rare. Therefore, the clinic and pathologic characteristics and treatments of these tumors are unclear. A 43 year-old married female with obstetric history of 3-0-2-3 (T-P-A-L) complained of pain in lower abdomen. Abdominal CT and MRI revealed corpus luteum in ovary. And HPV 18 test which is in high risk group was positive. After left pelviscopic paratubal cystectomy, pathologic result revealed the left salpinx as serous borderline tumor. Following up with paratubal serous borderline tumors are important because it is essential to decide the treatment and predict the prognosis of this tumor. The evaluation of the structure of cyst by ultrasonography and the performance of intraoperative frozen section analysis are important. Since most of these tumors are unilateral and confined to the fallopian tube or paratubal cyst and most patients are young, fertility-sparing surgery with comprehensive surgical staging procedures is acceptable, and adjuvant chemotherapy is likely unnecessary. Acceptable fertility-sparing procedures for young patients who desire to maintain childbearing include salpingectomy for fallopian tubal serous borderline tumors and paratubal cystectomy for paratubal serous borderline tumors.