Lead is one of the few elements with significantly varying isotopic comosition, a fact which can be used to distinguish between silver coins made of ores procured in different geological environments. This ideal relationship is compromised by the fact that ore bodies may overlap in isotopic composition and by remelting and mixing of metals used in ancient coins. The focus of this report, however, is early coins (from the Asyut Hoard, ca. 475 B.C.), which are less likely to have been made from mixed ores. Sampling and mass spectrometric techniques are described. Using an NBS standard, high reproducibility was achieved. The coins from the Asyut hoard may have been minted prior to 490 B.C. Laurian Galena ores are isotopically very similar to the analyzed coins, thus implying exploitation of that ore body before 490 B.C., earlier than the literary sources indicate. Further surveys of ore sources are necessary. Preliminary investigation of Aeginetic coins suggest two ore sources, but further investigation of these coins is required as well. In general, an approach focusing on the coins from one mint is favored. It is also suggested that chemical and isotopic analyses should be combined.