Presented is on overview of hairy cell leukemia problems in diagnostiky. Methods of diagnosis - both clinical (clinical course, laboratory findings) and histopathologic are described in detail. There are also immunophenotypic findings described. Furthermore, differential diagnosis together with therapeutic methods, and the prognosis of the disease are depicted, too.

        Key words: hairy cell leukemia - trephine bone marrow biopsy - immunohistochemistry - DBA.44 - 2- chlorodeogyadenosine - minimal residual disease