While the identification of the source of shells used as personal ornaments is crucial for determining home range and exchange networks of prehistoric hunter-gatherers, it is often difficult to identify the coastal versus fossil origin of the shells as most genera used as beads were available both at beaches and fossil outcrops. Here we present the first application of 87Sr/86Sr isotope dating to identify the origin of Upper Palaeolithic shell beads. We analysed four out of a collection of one thousand Dentalium shells associated to the La Madeleine child burial dated to 10; 190G100 BP and one Dentalium from the occupation layers of this site. 87Sr/86Sr ratios indicate that shells were collected by Late Upper Palaeolithic beadworkers on far away beaches rather than at nearer Miocene outcrops. This may be due to the narrowness of Miocene Dentalium shells, incompatible with the size of bone needles used to sew these shell beads on clothes.