Studies undertaken several years ago indicated little change in cattle size in Portugal before the fifteenth century AD, indeed even Roman cattle were not very different from preceding Iron Age ones. The Roman province of Lusitania com- prised the southwestern part of the Iberian Peninsula (present-day central and southern Portugal and Spanish Extremad- ura). Here we present some evidence of cattle size increase in the newly founded Lusitanian Roman cities, that is, those with no previous occupation. These cities include, for example, Emerita Augusta (Mérida, Spain) and ancient Ammaia (near Marvão, Portugal). We compare their measurements with those from smaller Roman towns and sites from other periods. Our hypothesis is that the size increase reflects better nourishment or the presence of different cattle morpho- types (by selection or introduction of new animals). Osteometric analyses suggest that cattle from the main Roman cities were generally bigger in Roman newly founded cities, contrary to sites with pre-Roman occupation. Innovations could have been implemented via the import of new stock and/or new breeding strategies.