Flow cytometry has an important place in the diagnosis of acute leukaemia mainly for its rapidity and reliability in determination of cell lineage and developmental stage of pathological cells as compared with conventional methods. Although the method of flow cytometry has become nearly a routine approach for defining the surface membrane (to a lesser extent also intracytoplasmic) markers of leukaemic cells, it is a helpful means for detection of a wide range of additional antigens, proteins and processes going on in the cell. Flow cytometry detects minimal residual disease, early relapses and prognosis, which depends on the ability of cell proliferation and apoptosis, and also their resistance to given treatment.

        Key words: acute childhood leukaemia, diagnosis, flow cytometry, monoclonal antibodies