Ground penetrating radar (GPR) surveys have been carried out in order to characterise reflection patterns and to assess the method's potential for imaging palaeofluvial sediments in the Mass-Rhine former confluence area in the southern Netherlands. The results show that the deposits of meandering, braided and transitional river types produce characteristic radar facies. Representative examples of each of these river types were selected where the GPR data could be directly correlated with sedimentary information derived from exposures and detailed drilling, and geomorphological data could be supplied. Individual channels may be distinguished by the radar facies of their fills. The floodplains of the different river types also show a characteristic radar facies. In GPR data from the meander floodplain, parallel, dipping reflections represent point-bar structures, while irregular, intersecting small channel patterns that alternate with parallel continuous reflections are more typical in the braid plain. A transitional river type shows characteristics of both of these types. Typical examples of GPR sections recorded in each of the different fluvial palaeoenvironments are presented in an interpretative radar facies chart.