An 80-year-old white female developed clinical signs of a large choroidal malignant melanoma in her left eye. There were no signs of metastatic disease but an asymptomatic chronic lymphatic leukemia was discovered. Histopathologic examination of the enucleated left eye showed a mostly necrotic malignant melanoma of the choroid with areas of spindle B cell differentiation, episcleral extension and secondary angle-closure glaucoma with necrosis of the anterior segment of the eye. On the basis of immunocytochemical studies of the lymphocytic infiltrates in the iridal blood vessels, retinal blood vessels and the choroid, the leukemic disease was classified as B cell lymphoma of low malignancy (lymphoplasmacytoid immunocytoma). A reactive T lymphocytic infiltration of the conjunctival stroma was also noted. Patients with malignant melanomas of the uvea require exclusion of a second malignancy.