According to the obligations provided by the Legislative Decree 241/2000, this study was performed to evaluate the annual average concentration of radon in banking premises existing in Apulia. Passive detectors were placed in areas distant from sources of heat and/or air. The following information was gathered about the workplaces: their position regarding soil, external apertures (doors and windows), ventilation and air-conditioning systems, wall and floor characteristics. In 74 bank branches 324 measurements were carried out. The values ranged from a minimum of 2 Bq/m3 to a maximum of 848 Bq/m3; the mean concentration was 94,11 Bq/m3 (DS +/- 119,73). In 5 measurements the values exceeded the maximum limit of 500 Bq/m3; besides, 6 values was ranged from 400 to 500 Bq/m3. These data seem to be influenced by the geological features of the Apulian sub-surface with karst phenomena.