In Europe several pilot projects for the restoration of the native European flat oyster, Ostrea edulis, recently begun and recommendations to preserve genetic diversity and to conduct monitoring protocols have been made. In particular, an initial step is to test for genetic differentiation against homogeneity among the oyster populations potentially involved in such programs. Therefore we conducted a genetic study to (1) confirm and precise the pattern of weak but significant genetic differentiation between Atlantic and Mediterranean populations already observed at this scale, (2) identify potential translocations that could be due to aquaculture practices, (3) investigate the case of the populations at the border of the geographical range that had been observed as related despite their geographic distance. The data set encompasses the genotypes of 617 flat oyster samples from 14 populations and for 203 SNP markers.