Malignant melanoma of the nose and paranasal sinuses can be a devastating disease, typically presenting at an advanced stage, with a 5-year survival rate ranging between 20 and 30%. It is an uncommon process, often misdiagnosed both clinically and pathologically. We present the case of an 80-year-old man who had a 2-month history of progressively worsening left-sided epistaxis and nasal obstruction. Radiographic evidence indicated the presence of soft tissue in the left maxillary sinus and nasal cavity resembling massive nasal polyposis and chronic fungal sinusitis. Magnetic resonance imaging was not performed because the patient had a pacemaker. After endoscopic debridement of the soft-tissue mass, frozen-section analysis detected no evidence of tumor. The final pathologic diagnosis was malignant melanoma. Otolaryngologists should be familiar with the difficulties inherent in the diagnosis and management of sinonasal melanomas.