The spectre of methods for the diagnostics and differentiation of haemolytic anaemias, particularly for the establishment of congenital, autoimmune haemolytic, drug-conditioned and other anaemias is treated. The clear delimitation of an iron deficiency from a disturbance of the iron distribution is advantageously to be achieved by iron staining of the bone marrow and by a determination of serum ferritin. The value of the diagnostic methods in megaloblastic anaemia is classified according to newer knowledge, in which case the vitamin-B12-absorption test and the serum level determination of vitamin B12 by no means range in the first place. Long-term culture results of haematopoietic stem cells are particularly evident in the aplastic syndrome of the bone marrow and further haematological diseases concerning the establishment of the intensiveness of proliferation. The classification of the acute leukemias demands conventional as well as cytochemical staining methods; recently, it is essentially improved using monoclonal antibodies. In leukemias cytogenetic investigations are more and more attracted to the estimation of the prognoses. In lymphogranulomatosis among others functional disturbances of the cellular immunity, in the group of the non-Hodgkin-lymphomas haematological, protein-analytic and immunological laboratory investigations are methods supporting the diagnosis. Altogether is to be established that the haematological diagnostics has become more and more perfect, in which case apart from new techniques old approved methods are still further used.