Abstract This paper presents selected issues related to the use of 222 Rn in therapeutic treatments. Radon is a radioactive element whose usage in medicine for more than 100 years is based on the radiation hormesis theory. However, owing to the radioactive character of this element and the fact that its alpha-radioactive decay is the source of other radionuclides, its therapeutic application has been raising serious doubts. The author points to potential sources and carriers of radon in the environment that could supply radon for use in a variety of therapies. Except for centuries-long tradition of using radon groundwaters, and later also the air in caves and underground workings, the author would also like to focus on soil air, which is still underestimated as a source of radon. The text presents different methods of obtaining this radioactive gas from groundwaters, the air in caves, mining galleries and soil air, and it presents new possibilities in this field. The author also discusses problems related to the transportation and storage of radon obtained from the environment. Within radon-prone areas, it is often necessary to de-radon groundwaters that are intended for human consumption and household usage. Also, dry radon wells are used to prevent radon migration from the ground into residential buildings. The author proposes using radon released from radon groundwaters and amassed in dry radon wells for radonotherapy treatments. Thanks to this, it is possible to reduce the cost of radiological protection of people within radon-prone areas while still exploiting the 222 Rn obtained for a variety of therapies. With regard to the ongoing and still unsettled dispute concerning the beneficial or detrimental impact of radon on the human organism, the author puts special emphasis on the necessity of strictly monitoring both the activity concentration of 222 Rn in media used for therapeutic treatments and of its radioactive decay products. Monitoring should be also extended to the environments in which such treatments are delivered (inhalatoriums, baths, saunas, showers, pools and other facilities), as well as to the patients – during and after the radonotherapy treatments. It is also essential to monitor the dose of radon and its daughters that is received by persons undergoing radon therapy. This should facilitate the assessment of the effectiveness of these treatments, which may contribute to a fuller understanding of the mechanisms of radon impact, and ionizing radiation in general, on the human organism. This will make it easier to ultimately confirm or reject the radiation hormesis theory. It is also essential to monitor the effective dose that is received by medical and technical staff employed to deliver the radonotherapy treatments.