The primary malignant melanomas of sphenoidal sinus are very uncommon tumours. We are reporting a clinical case of a 56 years-old male who was sent from the Neurology Department with ocular pain and headache of several months evolution and without personal history. Exploration revealed a VIth palsy, diplopia and ptosis. The complementary imaging tests (CT and MR) showed and expansive tumour of the sphenoidal sinus involving the right cavenous sinus. A F.E.S.S. with biopsy was performed to confirm the diagnosis. Our patient was treated by Radiotherapy and after a 4 year follow-up period he is still alive. We have carried to a bibliographic review of this pathology whose differential diagnosis must be done with epidermoid carcinomas, adenocarcinomas and lymphomas on that location.