Primary sarcoma of the fallopian tube is a very rare neoplasm. We report the case of a 69-year-old woman affected with leiomyosarcoma of the left fallopian tube. Her chief complaint was lower abdominal pain. The preoperative diagnosis was a left adnexal malignant tumor based on pelvic examination, abdominal computed tomography, and magnetic resonance imaging. Following a laparotomy, she was ultimately diagnosed with a FIGO IIc fallopian tube leiomyosarcoma. She was treated with total abdominal hysterectomy, bilateral salpingo-oophorectomy, pelvic lymph node dissection, partial omentectomy, and low anterior resection for rectal invasion. The patient subsequently received adjuvant chemotherapy with pirarubicin and ifosfamide. Thirty months after the first therapy, a computed tomography scan revealed metastasis of the liver, lung, and supraclavicular lymph node. The patient died of the disease 39 months after the initial treatment.