Messapia (Greek: Μεσσάπια) is a former municipality in Euboea, Greece. Since the 2011 local government reform it is part of the municipality Dirfys-Messapia, of which it is a municipal unit. Its name derives from the ancient river Messapios, which runs in the middle of the island. Population 13,756 (2001). The seat of the municipality was in Psachna.