Computer-based three-dimensional reconstruction of serially cut light microscopic sections is being increasingly used in medical and biological research. Compared with conventional two-dimensional evaluation of histological sections, complex histotopographical relationships and structural details are easy to assess and could be imposingly visualized on the graphics screen. Because of the rapid progress in modern computer hardware, uncomplicated and fast reconstruction systems are available on standard personal computers. Therefore, 3D reconstruction is applicable for a wide range of investigations that warrant 3D exploration. Own results are presented and the principles of 3D reconstruction, as well as the problems and difficulties in this new technique, are discussed. The complex ameboid morphology of megakaryocytes in bone marrow of primary (idiopathic) osteomyelofibrosis is examined with this new method in combination with selective immunohistochemical staining procedures. 3D reconstruction can visualize the complexity of cytoplasmic and nuclear formation impressively. Moreover, the models generated permit exact quantitative measurements of cell morphology. The technique presented is a powerful tool for anatomical-morphological investigations and can furthermore increase our comprehension of complex histomorphological objects.