This article presents the results of a programme of chemical composition analysis carried out using LA-ICP-MS on the collection of Hellenistic gold coins minted in Bactria and held at the BnF. It considers the authenticity of some of the unique coins analysed (including the Eukratideion). The Hellenistic coinage of Bactria (Seleucid and Graeco-Bactrian) is the only coinage we are certain was struck in that region in antiquity and the article provides a characterisation of the signature of a “Bactrian” metal stock and discusses its appearance in other coinages and metal objects elsewhere in the ancient world.