A 76-year-old man with compressive optic neuropathy secondary to a retrobulbar mass was managed by orbitotomy and removal of the mass. The lesion proved histopathologically to be an unusual orbital melanoma with massive central necrosis. There was no histopathological evidence of congenital melanocytosis. Dermatological and systemic evaluation before and after orbital surgery revealed no evidence of primary melanoma elsewhere. The patient developed hepatic metastasis 2 years after excision of the orbital tumour. It appears that the melanoma was a primary orbital tumour and not a metastatic melanoma from an occult primary lesion.