Background: Primary melanoma of the ovary is very rare; fewer than 50 cases have been reported to date. The diagnosis is challenging and is usually one of exclusion of the more-common metastatic diseases. This article describes such a case in detail and reviews relevant literature. Case: A 58-year-old perimenopausal woman presented with a 2-month history of pain and distension of the abdomen. On evaluation, she was found to have bilateral ovarian complex cysts with ascites. In view of her elevated CA 125 level and positive ascitic fluid cytology, she underwent a staging laparotomy. The final histopathology was reported as a malignant melanoma of the left ovary within a cystic teratoma with metastatic involvement of the right ovary, peritoneum, omentum, and mesentery. Results: Following surgery, this patient was evaluated with a whole body F18 flourodeoxyglucose positron emission tomography/computed tomography scan to look for any probable site of primary or other metastatic areas that had not revealed any other sites of disease. She was referred to the medical oncology services of the Sri Venkateswara Institute of Medical Sciences, in Tirupathi, Chittoor District, AP, India, for further treatment. As of this writing, she had completed two cycles of temozolomide chemotherapy with few side-effects. Conclusions: Primary malignant melanoma of the ovary is difficult to diagnose without a component of teratoma. Even with teratomatous elements, this is a diagnosis that involves excluding more-common metastatic disease from a more-common cutaneous primary. ( J GYNECOL SURG 31:166)