[From the beginnings of radon therapy]

The renaissance of the radon therapy in several countries since the end of the Second World War is made the occasion for a review to the beginnings of this special form of radiotherapy. Initially the early history of radioactivity research is described which among others led to the detection of the emanation as daughter product of radium. After this followed the evidence of the emanation as constituent of the natural atmosphere. The establishment of its presence in spring-waters led to the knowledge that there are more than average concentrations of emanation in several mineral springs. In the second part of the article the therapeutic use of the natural radion springs initiated by this is described in its development and importance for Austria (Badgastein, St. Joachimsthal) and Germany (Bad Brambach) up to the beginning of the First World War.