A method and apparatus for automatically classifying abnormal and normal red blood cells is disclosed. The abnormal cells may be differentiated into mutually exclusive subpopulations. The individual hemoglobin characteristic for each red blood cell is measured and a hemoglobin parameter may be reported for each subpopulation of cells. Additionally, cell sizes are measured and the mean cell size and Wintrobe indices may be reported. The interior cell structures for red blood cells are analyzed and the cells are classified based on the presence or lack of a central pallor, their shape, size, and hemoglobin content.