The khlui is a vertical duct flute from Thailand. It originated before or during the Sukhothai period (1238-1583 CE) along with many other Thai instruments. But, it was officially recorded as a Thai instrument by King Borommatrailokkanat (1431-1488) during the Ayutthaya Kingdon (1351-1767).

It is a reedless instrument, generally made of bamboo, though instruments are also made from hardwood or plastic. After many generations of modifications, it survives to the present day as the khlui phiang aw.