A 35-year-old black man developed abrupt visual loss in his left eye. Ophthalmic examination revealed a deeply pigmented mass obscuring the optic disc, hemorrhagic retinopathy, and signs of central retinal vascular obstruction. Fluorescein angiography disclosed sluggish filling of the retinal blood vessels; ultrasonography disclosed an acoustically solid mass in the optic nerve head. Cytopathologic findings of a fine needle aspiration biopsy specimen demonstrated probable benign tumor cells, but melanoma could not be excluded. Histopathologic findings in the enucleated eye revealed a large, necrotic melanocytoma of the optic disc and hemorrhagic necrosis of the retina secondary to obstruction of the central retinal artery and vein. Melanocytoma of the optic nerve can undergo spontaneous necrosis and induce central retinal vascular obstruction. Abrupt visual loss in a patient with a melanocytoma does not necessarily imply malignant transformation.