The Bionaz area belonged to Valpelline parish until 1640. On July 29th, the same year, bishop Mons. Vercellin designated the chapel, dedicated to Santa Margherita, as parish church. The chapel was built in 1617 in Plan-de-Veyne, which became the main village in the area from then on. Difficult and dangerous roads, abundance of snow and distance were the reasons which induced the bishop to guarantee Bionaz "a priest who would say Mass, administer the sacraments and teach people their religion".

In 1795 two eminent French prelates, the archbishop of Paris, Leclerc de Juigné, and the bishop of Clermont, François de Boveto, took to the mountains in Bionaz to escape the revolutionaries’ persecution.

They got to the village of Léchère, crossing Col Collon, and lived there for several months, leaving a happy memory of their stay.

• The church
  

  The existing church was built in 1694. The bell-tower was erected a few years later. The churchyard was a cemetery until 1934.

  The façade is decorated with the image of Santa Margherita, the parish patron saint, flanked on one side by San Grato and on the other by San Bernardo (both from Aosta Valley), work of art by the painter Ettore Mazzini (1949).

  The interior with its central aisle, cross vault and raised presbytery, is of an elegant simplicity. Your attention is drawn to the three Baroque altars, recently restored, in painted and partly gilded wood.

• The chapels
  
  There are several chapels in the parish area:

  in Chentre, the chapel dedicated to San Rocco. People invoke his help in epidemics. The chapel was built in 1641;

  in La Servaz (Rey), the “Madonna delle Nevi” chapel, built in 1710 and rebuilt in 1958 (double bell-tower);

  in Pouillayes, the chapel dedicated to the “Madonna del Carmine”, built in 1714;

  in La Léchère the San Grato chapel, built in 1674 and restored in 1962;

  in Lo-Noailloz, beyond the artificial lake of Place-Moulin, the Sacred Heart chapel, opened on September 11th, 1955.

  You mustn’t forget the ancient Santa Maria Maddalena chapel in Prarayer, built sometime earlier than 1604, re-built in the 18th century, deconsecrated in 1934 and nowadays a ruin: until 1985 the water of the dam covered it several months a year. It would be worth saving it because, in the past, it was the destination of a procession which was well-liked by the inhabitants of the Valley. Mons. Achille Ratti, who was later to become Pope Pio XI (1922–1939), said Mass there.