Since ancient times the warm thermal waters of Euganean basin, Italy, have been used for therapeutic purposes. The radioactive characteristics, assumed in depth, are due, in particular, to radon gas, which when released during the therapies in the indoor thermal room, determines exposure for the workers. The preliminary results of the project, the purpose of which is to analyze the totality of thermal springs, are presented. The concentrations, obtained by gamma spectrometry, show a high variability, and are comparable to those in other thermal springs in Italy and abroad. Possible correlations with geophysical factors, such as the temperature and depth of springs, have been investigated. A gedstatistical analysis of the radon data has also been carried out, through the study of the experimental variogram, obtained by kriging one map of the radon concentration: such an approach is useful not only for mapping but also for giving one possible interpretation of the examined phenomenon through structural geologic characteristics.