Mesaio () is a village and a community of the Oraiokastro municipality. Before the 2011 local government reform it was part of the municipality of Kallithea, of which it was a municipal district. The 2021 census recorded 1,063 inhabitants in the community. The community of Mesaio covers an area of 27.896 km<sup>2</sup>.
The community of Mesaio consists of three separate settlements:
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