Primary acquired melanosis (PAM) of the conjunctiva presents as a unilateral, flat, patchy, non-cystic, and brown-pigmented lesion of the conjunctival epithelium. It is seen mostly in middle-aged, fair-skinned, and older, white patients. It is caused by the proliferation of atypical melanocytes in the epithelium that do not invade the subepithelial tissue unless there has been malignant transformation. Since it can occur in any part of the conjunctiva, it is important to examine the underside of the eyelid. This lesion can remain dormant for years or show slow progression. It is the most important precursor of conjunctival malignant melanoma with some 1–30% of cases following that course. There are no associated symptoms.