As late as the end of World War II (1945), cardiac surgery did not play a clinical role worldwide. Successful cardiac operations were singular events often caused by unexpected circumstances. In contrast, the first successful suture of a cardiac stab wound by Ludwig Rehn (1896 in Frankfurt am Main) followed after experimental investigation of this topic in the laboratory. With a certain justification, this event can be mentioned as the beginning of clinical cardiac surgery. Operative procedures in patients with constrictive pericarditis followed, at that time, the ideas of Ludolf Brauer (precordial pericardiolysis) and were developed to perfection by Viktor Schmieden (subtotal pericardiectomy) during the 1920s. The first successful pulmonary embolectomy was performed in 1924 by Martin Kirschner; up to this date the sometimes used method of Friedrich Trendelenburg, already described in 1908, remained without success. The first successful operation of a ventricular aneurysm by Ferdinand Sauerbruch (1931) and the first successful closure of a patent duct (Botalli) by Emil Karl Frey (1938) occurred during operations undertaken under the circumstances of a preoperatively incorrect diagnosis. The results of the important experimental work of Ernst Jeger (monography 1913) and the first catheterization of the human heart by Werner Forssmann (1931) were not noticed by the surgical community at that time. In contrast to the time before World War II, in which German surgery was at the forefront, after the war there was a commanding need to approach the scientific and clinical level that meanwhile had been developed in the western countries, while there had been a standstill in Germany caused by its isolation since 1933 and the war since 1939. Surgeons in western Europe, the United States of America, and in Canada proved to be real friends. After one to two decades, the international clinical and scientific standard could be reached at some sites. A widespread clinical care for all patients became possible only in the late 1980s. This development was hampered even more in the eastern parts of the country. Above-average efforts there, equalized the degree of clinical care in a few years. The co-operation between the German Cardiac Society (founded 1927) and the German Society for Thoracic and Cardiovascular Surgery (founded 1971) was of great benefit for this satisfying development.