Radon is radioactive and its origin in groundwater is principally linked to the content of its parent element, uranium or radium in bedrocks. However, an on-going research at the Department of Land and Water Resources Engineering shows that a number of factors other than bedrock may potentially influence the radon concentration in groundwater. These factors include: steepness of the terrain, soil type, distribution of uranium and the effect of fracture zone. This article presents an application of GIS and 3D visualisation to explore the radon problem in groundwater. After a GIS pre-processing, 3D visualisations of the thematic data were produced in order to see if the visual approach would be useful to preliminary identify possible relationships between the high concentration of radon and other parameters.