This chapter deals with the detailed methodology for leukemic cell cytochemistry such as myeloperoxidase stain, sudan black B, non-specific esterase, double esterase, periodic acid Schiff stain, acid phosphatase and neutrophil alkaline phosphatase score. It also gives techniques for immunofluorescence and alkaline phosphatase anti alkaline phosphatase (APAAP) methods for immunophenotyping of leukemias.