The txistu (Basque pronunciation: [ˈtʃis̺tu]) is a type of fipple flute that became an important symbol of the Basque folk revival. The name may come from the Basque word ziztu, meaning "to whistle," with a change in the "z" sound (similar to how zalaparta became txalaparta). This three-hole instrument can be played with one hand, leaving the other free to play a percussion instrument.

The earliest written record of the txistu dates to 1864. However, it was likely used earlier, though it is difficult to determine exactly when it first appeared. The txistu evolved from upright flutes that were common in Europe during the Late Middle Ages. At that time, traveling musicians, called minstrels, brought instruments to the Iberian Peninsula, where local people, including nobles and commoners, adopted and developed them. Early txistu players were often named in written records based on the tabor (a drum used with the flute): tamborer, tamborino, tambolín, tamborín, tamboril, músico tamboril, tamborilero, or tamboriltero. Later, when named after the flute itself, they were called in Spanish pífano, silbato, silbo, silbo vizcaíno, or chilibistero.

The three-hole flute was used by people in many parts of Spain and western Europe, not only in the Basque region. Later records show Basque names for the instrument, such as txilibitu, txirula, txirola, txürula, txulula, txilibitulari, or txilibistari. While some similar instruments fell out of use, the three-hole flute gained popularity during the Renaissance. By the 17th century, it had reached its modern length of 42 cm in the western Basque Country. In contrast, the shorter version, called txirula, remained common in the eastern Basque regions, such as Soule, Labourd, and Navarre. At this time, the flutes were typically made of wood, though some were made of bone.

Until the 18th century, the txistu was played with a tabor drum and did not require tuning. However, in the 18th century, the txistu became part of a cultural revival led by the Count of Peñaflorida, who promoted Basque Enlightenment ideals. This led to the addition of more txistus to the pair, which required tuning. The instrument was modified to produce a range of two octaves, and a larger version called silbote was created to accompany complex music with multiple melodies. Meanwhile, rural musicians continued using simple, handmade txistus, while urban players formed schools to teach the more advanced instrument.

At different times in its history, the txistu used reeds or metal mouthpieces to improve its sound. Some believe this relates to the Basque connection to iron and metalworking, while others suggest the change began during the 19th-century industrial revolution.

The oldest txistu melodies use a musical scale called the Mixolydian mode in G, which is the same as the seventh mode in Gregorian chants. More recent compositions are often in G major, but sometimes in natural or sharp F, or rarely in C. Some melodies use natural B in major F.

The Association of Txistularies in the Basque Country was formed in 1927 to support txistu players. The group has continued its work to the present, except during the period of Francoist Spain.