To assess the malignant potential of uveal melanomas from standard histopathologic material, a single microslide from each of 100 cases underwent computer-assisted measurement of nucleolar cross-sectional area. The standard deviation of 200 measurements per slide correlated well with survival of patients following enucleation for their ocular tumor. Furthermore, a statistical model calculated from these measurements effectively predicted survival for 50 additional cases. Additional investigation demonstrated the following features of this method: (1) a high level of reproducibility; (2) acceptable constancy among different levels of the same tumor; (3) a practical expenditure of resources (assessment of each case required less than 40 minutes of a technician's time and an apparatus costing approximately $20,00). This method--computerized histopathologic assessment of malignant potential (CHAMP)--thus provides the pathologist with a practical method for extracting prognostic information from standard H & E-stained microslides of uveal melanomas. Previous studies by other researchers suggests that a similar method might be effective in assessing the malignant potential of more common neoplasms.