Allagi is a village in Oichalia Municipality, in the regional unit of Messenia, in the region of Peloponnese, Greece. Allagi lies at 98 m above sea level, 0.8 km from the Taygetus mountains. It has 103 inhabitants (2021). The nearest city is Kalamata, 24 km to the southeast. Among the landmarks around are Messene (21 km), Temple of Apollo at Bassae (23 km) and Mystras (37 km). Among the natural features are Cave of Caiada (33 km).

Also written Αλλαγή.