Background: Primary fallopian tube carcinoma (PFTC) is a rare gynecological malignancy though its prevalence may be underestimated given that most 'ovarian' serous cancers originate in the fallopian tube. Its diagnosis is challenging due to its vague signs and symptoms on presentation and it is frequently under-diagnosed pre-operatively. Case Presentation: We present a case of a pre-menopausal woman who presented with vaginal bleeding. Her laboratory testing and physical examination were grossly unremarkable. Gynecologic ultrasound demonstrated multiple uterine fibroids and a double layer endometrium measuring 4.5 mm. More importantly, the left ovary was seen with a complex cyst with mildly echogenic fluid and a solid excerscence. These findings were suspicious for malignancy. The clinical and radiological findings with elevated CA-125 were consistent with a malignant process. Patient subsequently underwent a diagnostic laparoscopy, which required conversion to exploratory laparotomy, supracervical hysterectomy, bilateral salpingo-oophorectomy, right ureteral lysis, right para-aortic and right pelvic lymph node debulking and omentectomy. Biopsy of left fallopian tube and ovary revealed invasive high-grade serous carcinoma of fallopian tube, with involvement of lymphovascular spaces and with surface involvement. Peritoneal washings were negative for malignancy. She was diagnosed with a high-grade serous carcinoma of the fallopian tube after undergoing an endometrial biopsy, multiple imaging tests and finally surgical intervention that yielded the diagnosis. She was started on chemotherapy with carboplatin and paclitaxel. Conclusion: Our aim is to highlight the importance of having PFTC among the differential diagnosis when women present with vaginal bleeding or abdominal pain, as the clinical presentation of PFTC tends to be non-specific, and is often under-diagnosed; reviewing the diagnosis and management, and characterizing the similarities and differences of PFTC with other gynecological malignancies such as ovarian cancer.