This pilot study comprises quantitative ultrastructural investigations of the normal, non-leukemic granulopoiesis in the bone marrow of four patients suffering from heart diseases, compared with the granulopoiesis of four patients with different types of CMPD. By evaluation of the morphometric parameters it could be demonstrated that normal granulopoiesis is subject to a strong functional order of organelles in the course of maturation, aiming at the preparation of mitoses of immature cells and the production of functionally capable specific granules. Contrary to this, the studied cases of CMPD exhibited striking differences of morphometric parameters, which may be interpreted as functional deficiencies or defects of organelles involved in the production of specific granules, with the phenomenon of dissociation of nuclear and cytoplasmic maturation.