The purpose of this research is to present the results of in situ radiation dose measurements for patients treated in the mofette of Covasna Sanatorium, Romania. The vertical distribution of the radon activity concentration was monitored indoor, in the treatment room and the staff room of the sanatorium respectively. The effective dose that may be received by patients during one cure of treatment is situated in the interval of 0.026-0.19 mSv. During these treatments the curative effects of the exposure to mofette gas may be correlated to the radon concentration at the nose level. The radiation dose on patients under our measurement conditions is below the reference level. The annual effective dose for workers may reach up to 0.768 mSv, indicating the necessity of personal dosimeters for a reliable monitoring of the occupational exposure.