Theisoa is a mountain village in the municipal unit Andritsaina, Elis, southwestern Greece. Theisoa is situated on a mountain slope above the left bank of the river Alfeios, 3 km southeast of Matesi, 3 km northeast of Rovia, 6 km northeast of connected Andritsaina and 8 km northwest of Karytaina. The Greek National Road 76 passes through the village.