To report clinical variations and the natural course of melanocytoma of the optic disc. A retrospective study was conducted on a consecutive series of patients with melanocytoma of the optic disc who were evaluated at the Ocular Oncology Service at Wills Eye Hospital. Demographic information and variations in appearance and size of the tumor and local ocular complications were noted. Frequency of tumor growth and malignant transformation was recorded. Clinical factors, including patient data and tumor features, were analyzed for their impact on visual acuity loss of 2 or more Snellen lines and the tumor growth, using Cox proportional hazards regression models. Kaplan-Meier survival estimates of probability of visual acuity loss of 2 or more Snellen lines and probability of tumor growth were performed as a function of time from the initial examination. Visual acuity loss of 2 or more Snellen lines, tumor growth, and malignant transformation of the tumor. There were 115 patients (116 eyes) with melanocytoma of the optic disc. The mean age at diagnosis was 50 years; 38% of patients were male and 62% of patients were female; 65% of patients were white, 29% of patients were African American, and 6% of patients were Asian, Hispanic, Indian, or Arabic. The lesion was unilateral in 99% of patients. Visual symptoms that seemed to be related to the melanocytoma were present in 24% of patients, and an afferent pupillary defect was noted in 9% of patients. Associated ocular abnormalities included ocular melanocytosis (8%), racial melanosis (7%), optic nerve hypoplasia (2%), and retinitis pigmentosa (1%). The melanocytoma was dark brown to black in 100% of patients. The mean tumor diameter was 2 mm and the mean thickness was 1 mm. Associated findings included a choroidal component (54%), retinal component (30%), optic disc edema (25%), retinal edema (16%), localized subretinal fluid (14%), retinal exudation (12%), retinal hemorrhage (5%), vitreous seeds (4%), and retinal vein obstruction (3%). Fluorescein and indocyanine green angiography typically showed persistent hypofluorescence of the lesion. Using Kaplan-Meier survival curves, related visual loss occurred in 18% of patients by 10 years, and minor tumor enlargement occurred in 11% of patients by 5 years and in 32% of patients by 10 years. Malignant transformation was documented in 2 patients (2%). Although melanocytoma of the optic disc generally is considered to be a benign, stationary lesion, it can produce several local complications, can cause visual loss, can grow slowly, and, rarely, can undergo malignant transformation into melanoma. Patients with optic disc melanocytoma should undergo periodic ocular examination.