ABSTRACTDevelopment of more time‐efficient and airborne geophysical data acquisition systems during the past decades have made large‐scale mapping attractive and affordable in the planning and administration of e.g., groundwater resources or raw material deposits. The handling and optimized use of large geophysical data sets covering large geographic areas requires a system that allows data to be easily stored, extracted, interpreted, combined and used one time after another with different purposes. Such an integrated system for management and utilization of hydrogeophysical data on a national scale has been developed during the past decade in Denmark.This data handling system includes a comprehensive national geophysical data base (the GERDA data base), a national data base for borehole information (the Jupiter data base), a program package for processing, interpretation and visualization of electrical and electromagnetic data as well as preparation of these data for upload to the geophysical data base (the Aarhus Workbench) and finally a 3D visualization and modelling tool used for geological modelling and data quality control. The Aarhus Workbench program package allows visualization and analysis of subsets of data from the geophysical data base, which may include data from many individual mapping campaigns. The 3D visualization and modelling tool uses data from the geophysical and the borehole data bases directly; moreover, it handles maps and grids produced in the Aarhus Workbench.The integrated system for management of hydrogeophysical data allows management of large amounts of data collected over several years in different mapping campaigns, of different consultant companies and with different geophysical methods and instrumentation. It is now used by all partners involved in the groundwater mapping in Denmark. The system promotes reuse of geophysical data and models in future mapping projects, as well as easing and promoting the use of geophysical data in the geological modelling. The integrated system secures transfer of documentation all the way from data acquisition over processing and inversion of the geophysical data to geological modelling through storage of data acquisition parameters, data processing parameters, inversion parameters and uncertainties on data and models in the geophysical data base.The benefits of the large amount of geophysical data gathered in the national geophysical data base and utilized by the two program packages are invaluable for all future groundwater planning and administration.