Digitized images of Feulgen-stained normal human B and T lymphocytes and monocytes were analyzed by computer and microphotometry. The algorithms assessed the chromatin distribution patterns. A substantial number of parameters descriptive of the chromatin distributions were found to show statistically highly significant differences between B and T cells and monocytes. Although the effects of a number of biologic variables, such as cell cycle phase and immune stimulation, need to be carefully evaluated, the preliminary results indicate potential for automatic classification and subclassification of human B and T lymphocytes in normal and disease states.