More attention has been given to improve workplace conditions in the last few decades, primarily to reduce the many different health risks. In the air that accumulates in underground workplaces radon may constitute such a health risk. The changes in the radon concentration monthly average in the show cave in Tapolca have been examined using SSNTD detectors for several years. The radon concentration in the show cave is especially high in summer months. The annual average (7342-10 370 Bq/m3) much higher, than the recommended action level (1000 Bq/m3). The radiation dose of workers originated from radon, were estimated on the basis of personal SSNTD radon detectors. The personal radiation dose is significant, especially for those employed during the whole year. Taking into consideration the calculated radon concentration, and the equilibrium factor F=0.4 (given in the literature), it approaches and even exceeds the dose limit of 20 mSv/year. With a well-organized work schedule, as well as the employment of outside workers during the summer period, the dose limit of 20 mSv/year can probably be maintained.