Russian stringed musical instrument of the lute family. It was developed in the 18th century from the dombra, or domra, a round-bodied, long-necked, three-stringed lute played in Russia and Central Asia. The balalaika is made in six sizes, from piccolo to double bass, and has a flat back and a triangular table, or belly, that tapers to the fretted neck. The frets are movable, and there is a small, round sound hole in the narrow end of the belly. The three strings, usually gut, are end hitched and strung over a violin-like, or pressure, bridge. They are normally plucked with the fingers, although metal strings are also plucked with a leather plectrum.

The instrument was used in folk music but was also employed in large balalaika orchestras in the 20th century. The representative size, called the prime, or treble, is usually tuned E–E–A in the octave above middle C.