The parish of Killehenny takes its Irish name, Cill Eithne, directly from a church dedicated to St Eithne, yet by 1615 the Royal Visitation of the Diocese of Ardfert could record of the vicarage: "No church nor never was." Whether that was bureaucratic exasperation or a genuine reflection of a long-vanished structure, no standing ruins have ever been documented. By 1841 the Ordnance Survey confirmed that nothing remained, and by 1942 the blowing sands along the coast near the River Cashen were already beginning to encroach on the graveyard itself. What can be seen today, according to a 2011 survey, is an undulating interior, the result of the graveyard sitting on the eastern edge of a coastal sand-dune ridge, and a cluster of older tombstones in the south-eastern corner that mark where the church once stood.

The medieval church was valued at 20 shillings per annum in the papal taxation of the Diocese of Ardfert in 1302, a modest assessment that places it firmly in the minor tier of ecclesiastical holdings. By 1483 the vicarage had become the subject of a more colourful dispute. A papal letter of that year noted that one William Nou, a clerk, had been holding the vicarage without any canonical right for between fourteen and sixteen years, his claim complicated by questions of illegitimacy, his parentage described in the letter in three alternative formulations as if the precise circumstances were themselves unclear. The pope resolved the matter by ordering the vicarage united to the deanery of Ardfert, assigning its benefits instead to Patrick FitzMaurice, a clerk of Ardfert described as being of noble birth on both sides. The saint for whom the church was named adds a further layer of ambiguity. Two Irish saints bear the name Eithne, with feast days falling on 6 June and 12 July respectively, and neither the Ordnance Survey in 1841 nor a survey carried out in 1942 could determine which of the two the parish church had originally honoured. By both accounts, her name and festival day had simply been forgotten locally.