True neoplasm of retinal pigmented epithelium (RPE) is rare, but because of important differential diagnosis including malignant melanoma (which is more common than adenocarcinoma of RPE), both in clinical and pathological characteristics, we are interested in reporting this case. A 60-year-old man underwent right eye enucleation because of progressive loss of vision and ophthalmologic diagnosis of malignant melanoma. Pathological findings revealed a lesion in posterior segment near the optic nerve. The mass was solid and well circumscribed. In histological evaluation, the tumor was composed of cells having large, pleomorphic and hyperchromatic nuclei, prominent nucleoli and occasional pigmentation. Tumor cells were mostly arranged in papillary pattern. For differentiation of melanoma, immunohistochemistry was done. Epithelial membrane antigen (EMA)was strongly positive and HMB45 was negative; consistent with the diagnosis of adenocarcinoma of RPE. Systemic evaluation ruled out any metastasis. In conclusion, although adenocarcinoma of RPE is rare, but must be kept in mind in differential diagnosis of malignant melanoma of choroids.