Abstract In a first clinical test, computer programs are being used to diagnose leukemias. The data set includes 20 000 cells from 120 different blood samples taken from 80 patients suffering from various hematological disorders. BMDP7M and CART statistical software test the classification power of the cell markers extracted by image processing. The feature distributions from the mononuclear cell population correlate directly to the specific leukemia. The computer methods and results presented here are part of an investigation to develop, refine and test computer aided methods in the diagnosis of blood malignancies. The data suggest the possibility of new diagnostic procedures in hematology.