Gusli (Russian: Гусли) is the oldest Russian multi-string plucked instrument. Its exact history is unknown, but it may have derived from a Byzantine form of the Greek kythare, which in turn derived from the ancient lyre. It has its relatives throughout the world - kantele in Finland, kannel in Estonia, kankles and kokle in Lithuania and Latvia. Furthermore, we can find kanun in Arabic countries and the autoharp in the USA. It is also related to such ancient instruments as Chinese gu zheng which has a thousand year history and its Japanese relative koto.

In the times of Kievan Rus’, the term gusli is thought to simply refer to any generic stringed instrument. The root of the term comes from the word to make sound in the wind. The term was eventually associated with the trapezoidal gusli-psaltyry (which may have originated in Byzantium).

The gusli is one of the oldest musical instruments that have played an important role in the Russian music culture. The Greek historians Theophylact Simocatta and Theophan were the first to mention the gusli: Under the war in the end of the 6th Century, the Greeks took Slavonic prisoners and found a musical instrument named the gusli. This corresponds to what the Arabic authors Al-Masudi and Ibn-Dasta told in the 10th Century AD.