Bionaz (Valdôtain: Bioun-a; Biona from 1939 to 1946) is a comune sparso which extends over 143 square kilometres (55 sq mi) of the North-Eastern Valpelline area of the Aosta Valley region of northwest Italy. The commune lies on the left side of the river Dora Baltea. The population of about 240 is dispersed among 20 or more small alpine villages and hamlets including Plan-de-Veyne, which is the main centre and the capoluogo (locally and officially also chef-lieu, in French). The commune belongs to the Unité des communes valdôtaines du Grand-Combin.

Villages, hamlets and other centres

The commune's statute designates the following frazioni (locally officially called hameaux, in French):

• Les Balmes
• Chentre
• Chez-Chenoux
• Chez-Noyer
• Chez-les-Merloz
• Les Crêtes
• Les Dzovennoz
• Lexert
• Les Ley
• Le Moulin
• Plan-de-Veyne
• Perquis
• Les Places
• Pouillayes
• La Quelod
• Les Rey
• Les Rus (Ru)
• Les Vagère
• Le Vianoz

The following localities, villages and other places not formally designated as frazioni, are also listed in the bulletin:

• Chamein
• Chez-Badin
• Le Clos-Neuf
• La Ferrère
• La Léchère
• Prarayer
• Propéraz

Mountain huts

Within the boundaries of the commune, there are also three mountain huts:

• Refuge Crête Sèche
• Refuge Prarayer
• Refuge Aoste
• Refuge Nacamuli au col Collon