Forty uveal melanomas were examined, half of which had proved fatal. Twenty cells were selected from each tumor, and six cytologic features were measured on each of these cells. It was found that the cells selected from fatal tumors had longer nuclei, more nucleoli, and greater nuclear pleomorphism than those selected from nonfatal tumors. Also, cells from melanomas classified as mixed cell type by the Callender classification had wider nuclei and longer nucleoli than those from tumors classified as spindle B cell type. Since the former cell type is associated with a worse prognosis, these features would probably assist in assigning prognosis to a large group of randomly selected malanomas. Thus, five nuclear characteristics (long nuclei, wide nuclei, long nucleoli, multiple nucleoli, and nuclear pleomorphism) should prove useful for predicting death from the dissemination of uveal melanoma.