Examinations of human mitotic chromosomes using an electron microscope since the last review in “Humangenetik” (Schwarzacher, 1970) were summarized. Three methods were used for preparation: ultrathinnsectioning, spreading- and critical point drying and a method for comparing cells in the light and electron microscope. These three methods showed that fibrils are the main elements of organization of chromosomes. Fibrils with a diameter of 20–40 A, of 100 A, of 250 A and thick fibrils (bundles) of 500–1000 A thickness were described. A comparison of chromosomes in the light and electron microscope showed, that metaphase chromosomes can be characterized by the number of their primary coils. Examinations of Giemsa-banding techniques with electron microscope showed fibrils as being clearly visible. G bands are coils of thick fibrils (up to 1000 A). The methods based on these new results were discussed.