The patron saint of Jelsi is the apostle Saint Andrew, celebrated on 30 November in the mother church dedicated to him, dating from the 10th-11th century: the current portal bears the date 1705, but the original was Romanesque, with twisted colonnettes and capitals adorned with stylised palmettes. In the side aisles stand the statues of Saint Andrew and of Saint Anne, co-patron, together with many other saints venerated in the town.
Co-patron Saint Anne is at the heart of Jelsi's most important and best-known event, the wheat festival, celebrated every year on 26 July. The tradition began as thanksgiving for the light damage suffered by the community after the violent 1805 earthquake, which devastated part of Molise but almost entirely spared Jelsi, a fact attributed to a divine miracle; participation grew further after the town also escaped a violent hurricane that struck on 24 and 25 July 1814. Having become since the second half of the 20th century one of the most representative festivals of Molise and Italian agriculture, it involves the organising committee choosing, at the end of June, one of the best wheat fields in the area and beginning the harvest: the sheaves gathered are carried through the town's streets, where groups of Jelsi residents braid kilometres of wheat plaits to stretch out as festoons along the main street, awaiting the 26 July parade, when about forty ox-cart and wagon loads process through the town.
