A 42-year-old woman developed a ciliary body mass which indented the lens equator and produced a dense focal cataract in the right eye. The clinical diagnosis was malignant melanoma of the ciliary body, and the lesion was removed by a large iridocyclectomy. Histopathologic examination revealed an acquired adenoma of the non-pigmented ciliary epithelium. The clinical and histopathologic features of this rare intraocular tumor are discussed with emphasis upon its differentiation from malignant melanoma.