Isthmia may refer to:
Isthmia (sanctuary) at the east side of the Isthmus of Corinth, Greece The ancient Isthmian Games, held at the sanctuary Temple of Isthmia, located in the sanctuary Isthmia, Corinthia, a village in the municipal unit Loutraki-Perachora, Corinthia, Greece, near ancient Isthmia Isthmia (genus), a genus of diatom in the Mediophyceae class