Synchronized evidence of bilateral ovarian masses with an asymptomatic  incidental appendiceal solitary mass is an unusual  event during  operation.  The main differential diagnosis in this status  is metastatic mucinous adenocarcinoma of ovary to appendix  versus  metastatic mucinous neoplasm of appendix  in both side ovaries. Herein, i present a  metastatic bilateral ovarian high grade serous carcinoma to the appendix as  a diagnosis pitfall. A 43-year-old woman, with menstrual irregularity was referred. Imaging studies  showed bilateral ovarian masses. She underwent total abdominal hysterectomy, bilateral salpingo oophorectomy , omentectomy,  pelvic lymph nodes dissection and appendectomy.  Final diagnosis, according to histopathological and immunohistochemical findings was metastatic bilateral ovarian high grade serous carcinoma of the appendix. These tumor markers may be useful for final diagnosis because tumoral tissue expression of them is not 100%. Therefore usage of several of them in correlation with histopathology findings, definitely helpful.