Ancient copper soins from the Greek cities Nikopolis in Epirus and Thessaloniki in Macedonia, minted during Roman imperial times (31 BC to AD 268), were analysed non-destructively by proton induced X-ray emission, after removal of the patina. An intercomparison study using different analytical methods was also performed on five coins. Eleven elements were analysed quantitatively on all coins. Statistical analysis of the results was performed for their presentation in the form of dendrograms. Finally, the variations in the concentrations of some individual elements from emporer to emporer were examined.