Primary malignant melanoma may rarely arise in the orbit, where melanocytes are usually absent. A 43- year old man presented with painful, profuse, unilateral, eccentric proptosis for 1 year. Computed tomography scan showed intra-ocular mass in posterior chamber of right globe with coarse calcification and contiguous retrobulbar mass. The patient gave consent for surgical exploration where a well-defined pigmented mass was seen enchasing the optic nerve. Histopathological workup revealed it to be malignant melanoma. Metastatic workup came out to be negative. Right eye lid sparing exenteration was done. Hence in patients presenting with massive unilateral proptosis, primary malignant melanoma though extremely rare should be one of the suspects.