Aigio, also written as Aeghion, Aegion, Aegio, Egio, is a town and a former municipality in Achaea, West Greece, on the Peloponnese. Since the 2011 local government reform, it is part of the municipality Aigialeia, of which it is the seat and a municipal unit. Aigio is the second largest city in Achaea after Patras. The municipal unit has an area of 151.101 km2. It has a population of around 26,000 while the municipality has about 49,000 inhabitants.