The inhabitants of the commune are known as Amendüztar.

Amendeuix-Oneix is located some 50 km east by southeast of Bayonne and 40 km south-west of Orthez in the Mixe country in the former Basque province of Lower Navarre. The village can be accessed by the D124 road from Garris in the west passing northeast to the village then continuing north to join the D29. The D11 road also passes through the south of the commune from Garris to Saint-Palais. The small D511 road links the D11 to the D124 within the commune.

Located in the Drainage divide of the Adour, the northern part of the eastern border of the commune is the Bidouze which flows north to join the Adour west of Peyrehorade. The southern part of the eastern border consists of the Joyeuse with many tributaries rising in the commune including the Algueruko erreka, the Sallarteko erreka, and the Soubiaga erreka. The Aitzeguerris rises just south of the village and flows into the Bidouze.

The current Basque name is Amendüze-Unaso. Jean-Baptiste Orpustan suggested that Oneix means the 'place of abundant hills'. Brigitte Jobbé-Duval however suggested that Oneix came from the Basque Unanu which means the Asphodelus (plant) and signifies a "place where the asphodelus is abundant. She also suggested that the origin of Amendeuix was Aquitane-Roman to designate a noble domain.

The following table details the origins of the commune name and other names in the commune.

Sources:

• Orpustan: Jean-Baptiste Orpustan, New Basque Toponymy
• Raymond: Topographic Dictionary of the Department of Basses-Pyrenees, 1863, on the page numbers indicated in the table. (in French)
• Cassini: Cassini Map from 1750

Origins:

• Notaries: Notaries of Labastide-Villefranche
• Pamplona: Titles of Pamplona
• Pau: Titles of the Chamber of the Counts of Pau
• Biscay: Martin Biscay

In the 16th century (1594), evidence of witchcraft was reported by an admonition to the States of Navarre by the Prosecutor of Mixe (together with those of Arberoue, Ostabaret, Irissarry, Ossès, Baigorri, and La Bastide-Clairence), who complained of a lack of prosecution and requesting that each town or district of Lower Navarre elect "two men of good character who are not suspects to find and punish the perpetrators of these crimes of witchcraft, apostasy, and magic: to be joined with the people of Roy and all at the expense of those convicted or, in case of insolvency, to those countries and places which will be instructed". Part of this admonition followed a request from the inhabitants of Amendeuix dating from 1587 who claimed to have been victims of "spells that were manifested mainly by evil barking".

The village of Oneix joined with Amendeuix to form the commune of Amendeuix-Oneix on 27 August 1846.

Blazon: Quarterly, 1 and 4 of Or with an Oak vert debruised by a boar of sable at the foot of the tree; at 2 and 3 party per fesse wavy of argent and azure.

This list is incomplete; you can help by adding missing items. (April 2021)

List of Successive Mayors

The commune belongs to seven inter-communal structures:

• the Communauté d'agglomération du Pays Basque
• the AEP Association for Mixe country
• the sanitation association for Saint-Palais - Luxe-Sumberraute
• the association for school buses of Amendeuix-Oneix and Gabat
• the energy association for Pyrénées-Atlantiques;
• the inter-communal association for the operation of schools in Amikuze
• the association supports Basque culture

In 1350 nine fires were reported in Oneix and 15-18 in Amendeuix.

The fiscal census of 1412-1413, made on the orders of Charles III of Navarre, compared with that of 1551 men and weapons that are in this kingdom of Navarre this side of the ports, reveals a demography with strong growth. The first census indicated the presence of 13 fires in Amendeuix with the second showing 40 (33 + 7 secondary fires). The same census reported 8 fires in Oneix in 1412-1413 against 17 (14 + 3 secondary fires) in 1551.

The census of the population of Lower Navarre in 1695 counted 63 fires at Amendeuix and 20 at Oneix.

In 2017 the commune had 448 inhabitants. The population data given in the table and graph below include the former commune of Oneix.

Historical population

Year Pop. ±% p.a. 1793 341 —     1800 406 +2.52% 1806 416 +0.41% 1821 409 −0.11% 1831 446 +0.87% 1836 460 +0.62% 1841 433 −1.20% 1846 424 −0.42% 1851 412 −0.57% 1856 389 −1.14% 1861 372 −0.89% 1866 376 +0.21% 1872 391 +0.65% 1876 353 −2.52% 1881 363 +0.56% 1886 385 +1.18% 1891 335 −2.74% 1896 336 +0.06%	Year Pop. ±% p.a. 1901 342 +0.35% 1906 361 +1.09% 1911 360 −0.06% 1921 352 −0.22% 1926 321 −1.83% 1931 336 +0.92% 1936 295 −2.57% 1946 297 +0.07% 1954 294 −0.13% 1962 286 −0.34% 1968 289 +0.17% 1975 329 +1.87% 1982 327 −0.09% 1990 381 +1.93% 1999 367 −0.42% 2007 412 +1.46% 2012 428 +0.76% 2017 448 +0.92%
Graphs are unavailable due to technical issues. Updates on reimplementing the Graph extension, which will be known as the Chart extension, can be found on Phabricator and on MediaWiki.org.
Source: EHESS and INSEE

The commune is part of the Appellation d'origine contrôlée (AOC) zone of Ossau-iraty.

According to the Map of the Seven Basque Provinces published in 1863 by Prince Louis-Lucien Bonaparte the dialect of Basque spoken in Amendeuix-Oneix is eastern low Navarrese.

Two churches in the commune are registered as historical monuments:

• The Church of Saint Peter (1787) at Oneix.
• The Church of Saint John the Baptist (1903) at Amendeuix.

The commune has a kindergarten.

Amendeuix, Gabat, Ilharre, and Labets-Biscay have partnered to create an inter-educational grouping (RPI).

• Communes of the Pyrénées-Atlantiques department

• in the Bernardo Estornés Lasa - Auñamendi Encyclopedia (Euskomedia Fundazioa) (in Spanish)
• Amenduix and Oneix on the 1750 Cassini Map

Wikimedia Commons has media related to Amendeuix-Oneix.