The Adriatic Sea and Balkan Peninsula were an important corridor for the spread of agriculture northwards and westwards from the Near East into Europe. Therefore, the pace and nature of the Mesolithic-Neolithic transition along the Adriatic coastline has important implications for the movement of new peoples and/or ideas during one of the most eventful periods in European prehistory. We present new Early Neolithic radiocarbon and stable isotope evidence from humans and animals from the Zemunica cave site in Dalmatia, Croatia. The results show that these humans date to the earliest Neolithic in the region, and they have completely terrestrial diets, where the main protein source was most likely to have come from domesticated animals. Data are then compared to previous isotope and archaeological evidence to explore models for the spread of agriculture along the eastern Adriatic coast.