Breast carcinoma metastasis to the fallopian tube is extremelyrare. Distinction between a primary fallopian tumor and metastasisof breast cancer is crucial since treatment and prognosis aredifferent. However, it is difficult to confirm pathologically withoutsurgery. Herein, we report a 46-year-old woman with a historyof left modified radical mastectomy for breast cancer 13 yearsago, presenting with a left adnexial mass. She underwent totalabdominal hysterectomy with bilateral salpingo-oophorectomy.Pathology findings revealed cytokeratin (CK) 7, ER, and PRpositive tumor cells. Mammoglobuline, P53, CK20, GCDFP-15and, thrombomoduline were negative. HER2 was also 2+.Fluorescence in situ hybridization (FISH) for HER2 was negative.Based on the morphology and immunophenotype of the tumor,we established the diagnosis as metastasis of breast cancer to thefallopian tube.