An ethnobotanical field study was conducted among the Croatians living in ]i}arija in northern Istria and a very restricted folk pharmacopoeia (of approximately only 30 remedies) was recorded. This finding suggests that a remarkable process of erosion of Traditional Knowledge (TK) may have taken place. The collected data were compared with the ethnobotanical findings of a field study previously conducted among the Istro-Romanians living in the nearby village of @ejane, who probably migrated there around the 14th Century. It was found that more than half of the botanical taxa were being used medicinally across the two communities, and that approximately one third of the actual medicinal plant uses were recorded in both communities. Correspondence analysis carried out comparing the same data with those of the ethnobotanical literature of Istria and Friuli-Venezia Giulia in North-Eastern Italy showed that the folk phytotherapy of the diverse ethnic populations living in multi-cultural Istria appears to be very similar.