With the increased availability of antibodies and fluorochromes and the improvements in instrument hardware and software, flow cytometry (FCM) immunophenotyping has become a popular and useful diagnostic tool in the hematopathology laboratory. The utility of FCM immunophenotyping is multifold, as it facilitates (1) the distinction between neoplastic and benign conditions, (2) the diagnosis and classification of lymphomas and leukemias, (3) the assessment of other neoplastic and pre-neoplastic disorders such as plasma cell dyscrasias and myelodysplastic syndromes, and (4) the detection of minimal residual disease in patients with acute leukemia or chronic lymphoid leukemia. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.