The trikiti (standard Basque, pronounced [trikiti]), trikitixa (dialectal Basque, pronounced [trikitiʃa]), or eskusoinu txiki ("little hand-sound," pronounced [es̺kus̺oɲu tʃiki]) is a two-row Basque diatonic button accordion. It has right-hand rows keyed a fifth apart and twelve unisonoric bass buttons. The word trikitixa, which sounds like the noise of a tambourine, originally described a traditional Basque musical group. This group included the trikitixa instrument, along with others like the alboka, txistu, and additional instruments.

The trikitixa was likely brought to the Basque region by Italian immigrants from the Alps. The first written record of the trikitixa dates back to 1889, when a diatonic accordion was used during a popular pilgrimage festival in Urkiola (Biscay). In 1890, a trikiti appeared in a photograph from Altsasu (Navarre), a railway junction. Some believe the instrument was imported to the Basque Country through the port of Bilbao, while others suggest Italian railway workers from the Alps brought it. The diatonic button accordion was invented in Vienna in 1829 and later spread across Europe.

A pair of diatonic button accordions and a tambourine became popular in local and community celebrations. Young people danced to their music, including traditional dances like fandangos and arin-arin. However, the Catholic Church opposed this music, calling it "hell's bellows" because its lively sound encouraged dancing, which the Church considered tempting.

The playing style of the trikiti remained the same until the 1980s, when Kepa Junkera and Joseba Tapia introduced new ways to play the instrument. Though some criticized their methods, these innovations became accepted. Today, both traditional and modern styles of trikiti playing coexist. Influences from Tejano musicians like Flaco Jiménez and other international players have also shaped the instrument's development. Other well-known trikiti players include Alaitz Telletxea, Iñaki Malbadi, Maixa Lizarribar, Xabi Solano, Xabi Aburruzaga, Iker Goenaga, and the Catalan musician Carles Belda.

Today, traditional trikiti ensembles typically include two trikiti players, a tambourine, and a singer. The music is played with fast, decorated notes and short, quick rhythms called staccato triplets.