Inishmacsaint () is a monastery located on an island off the western shore of Lough Erne, County Fermanagh, Northern Ireland. The site includes the ruins of a monastic church and an early stone cross, probably from the tenth and twelfth centuries. Inishmacsaint was founded by St. Ninnidh, (d. 523/30). The original monastic buildings were probably damaged or destroyed during the raids of the ninth or tenth centuries.