The authors report a case of a malignant melanoma of the nasal cavity that is a rare tumor and very aggressive, constituting 1% of all melanomas. It appeared in a patient 54 years after he was treated for a hereditary retinoblastoma. Its symptoms are nonspecific, and often marked by epistaxis. Its diagnosis is histological, supported by immunohistochemistry. Its prognosis is often unfavorable, and characterized by the occurrence of metastases and recurrences. Because of the risk of secondary cancer that exists in any survivor of hereditary retinoblastoma, we must think of possible mucosal melanoma of the nasal sinus in these patients in cases of chronic epistaxis. The prognosis of this tumor depends on its early diagnosis and surgical treatment.