Electrocardiography celebrates hundred years of its existence. The historical article on the cornerstones of its development was written on request of the editorial board of Vnitrní lékarství (Internal Medicine) and the Czech Society of Internal Medicine. After summarizing the beginnings of the discovery of bioelectric current and attempts of its registration the author describes the construction of the string galvanometer by Willem Einthoven. In 1901 and 1903 he published the first findings on the application of electrocardiography in man. Therefore that years are considered the years when clinical electrocardiography was born. Next we deal with the development of lead systems and modern electrocardiographs, incl. the discovery of the Braun tube, the construction of monitors, vectorcardiography and spatiocardiography. The author summarizes the principles of rational interpretation of the surface electrocardiogram and analyzes further modifications such as the use of leads from the right hemithorax, oesophageal leads, stress electrocardiography. Classical surface electrocardiography is probably a completed discipline. It will remain also in future a basic auxiliary examination method in internal medicine and allied disciplines. Due to its importance however classical electrocardiographic examination should be shifted into primary care where it may be a great enrichment and acceleration of the diagnostic process. Further development of electrocardiology is focused on non-invasive and invasive examinations and in particular treatment of arrhythmias where surface electrocardiography will be also in future important as a reference signal for the time localization of electric potentials of the intracardial electrocardiogram and programmed electrical stimulation.