The nave is made up of two bays dating from the 12th century; with its double arch and its broken barrel-vaulting, it is a fine example of the late-Romanesque. The choir and the lower wings were added to or renovated over succeeding generations up to the 16th century. The present appearance of the walls and the vaulting bears witness to these numerous additions and modifications over three to four hundred years. Particularly of note are the highly decorated pendants at the base of the ogives.
The bell-tower, of the type known as a clocher à peigne, characteristic of churches throughout the southern Massif Central, was ordered to be dismantled by Louis XIV to punish the parish of Ailhon for its participation in the revolt of Roure. It was rebuilt with four niches for four bells, but now it houses only two: during the 19th century the inhabitants of the neighbouring villages of Lentillères and Fons decided to construct their own churches and to leave the parish of Ailhon, each taking with them a bell.
Dedicated to St Andrew, Ailhon church, which is part of the parish of St Benoit-d’Aubenas, hosts Mass once a month and is also used to hold concerts throughout the year.