In recent decades interest in finds of irregularly issued Roman coins in the Central and Eastern European Barbaricum has increased significantly. In the area of the Przeworsk culture, the starting point was excavation of a Roman and Migration period settlement in Jakuszowice where a significant number of subaerati were identified. Over the last few years the intensification of the process of coin find registration and the increased number of archaeological excavations of Roman and Migration period settlements in western Lesser Poland have resulted in a significant increase in the material available for research. This new research demonstrated the presence of irregular Roman denarii other than subaerati (e.g. tin-lead bronze imitations). In this paper we present the results of the analysis of coin finds from twenty Roman and Migration period settlements in western Lesser Poland, with particular reference to irregular issues.