Foredunes are the foremost dunes formed on the backshore of beaches by aeolian sand deposition trapped by vegetation. Many recent studies, on the world, have shown that ground penetrating Radar (GPR) method can give good and useful results over the modern foredunes. Nevertheless none of these studies were performed on a macro-tidal environment. Our study is focused on the active and relic foredunes from the Regneville inlet (Normandy, France) in a macro-tidal context. We performed the GPR acquisition by using three different antennae of frequency 100, 250 and 500 MHz, respectively. The topography of all GPR profiles was recorded on the same time using a differential GPS which gives a precision of centimeter. The processing of all GPR profiles has been performed with in-house software written in Matlab. The filtered migrated radar sections, obtained with 100, 250 and 500 MHz antenna, were visually analyzed for data interpretation. Our interpretation methodology consists of picking all the reflectors on the migrated GPR profiles obtained with different antennas. Afterwards we superimposed them on a single image containing the picking reflectors for each frequency. The picking reflectors combined with direct field observations on trenches or/and natural outcrops, allow defining better the internal architecture of foredunes.