We report a rare case of malignant melanoma arising in a cystic teratoma of the ovary occurring in a 60-year-old woman who died in four months despite the combined treatment administrated (surgery and chemotherapy). Diagnosis of ovarian melanoma was confirmed by immunohistochemical positivity to S-100 protein and HMB 45. There was no evidence of extra-ovarian primary melanoma on clinical examination; therefore the diagnosis was primary ovarian melanoma. Melanoma metastases were detected on the uterus, the right ovary, the omentum and in one of the three excised left external iliac lymph nodes. A review of the literature is analyzed and discussed.