Visual disturbance in 11 patients with melanocytoma of the optic disk was analyzed. Goldmann visual field examination showed enlargement of Mariotte's blind spot in 7 of 10 patients (70%) and visual field defect or depression in 7 patients (70%). In 6 of the 7 patients with visual field defect of depression (86%), the portion of visual field damage corresponded with the location of the tumor and retinal nerve fiber bundle defect. In 1 patient, sudden loss of visual acuity occurred, presumably due to anterior ischemic optic neuropathy induced by melanocytoma.