Gynandroblastoma, an extremely rare ovarian tumour that usually consists of both Sertoli stromal cell and granulosa cell tumours, often produces both androgenic and estrogenic effects. The authors herein report a case of gynandroblastoma with the longest diseasefree period reported to date. A 66-year-old woman without metrorrhagia or hirsutism presented with abdominal pain and slightly elevated serum estradiol levels. Her uterus was enlarged, and endometrial curettage performed to reduce endometrial thickness prior to laparotomy led to a diagnosis of atypical endometrial hyperplasia. She was diagnosed of ovarian tumour. The pathology report revealed that the right ovarian tumour was a "gynandroblastoma". Such lesions are classified as borderline malignant. Postoperative adjuvant therapy was not administered in this case because only a few recurrent or fatal cases have been reported. The lesion was classified as pT1aN0M0 according to Union for International Cancer Control (UICC). The patient is alive and has been disease-free for 77 months post-surgery.