It is a little surprising, but radon has been measured by our Institute for >50 y. In the first phase this was carried out in underground mines (up to the present day) but more and more attention has been paid to domestic dwellings and NORM workplaces. The number of the measurements (grab sampling underground, SSNTDs application) was relatively high. To the routine work of the Institute is added research and calibration for radon measuring organisations. Since the formation of the Czech Republic, our previous institution was reformed by the State Office for Nuclear Safety and is one of the two organisations whose main task is, among others, radon measurement.