The arpeggione is a six-stringed musical instrument that has frets and is tuned like a guitar. However, it has a curved bridge that allows it to be bowed, like a cello. This makes it similar to the bass viola da gamba. The instrument is sometimes called a guitar violoncello. It is essentially a bass viol with a guitar-like tuning: E–A–d–g–b–e'. The body shape of the arpeggione resembles a medieval fiddle more than a guitar or bass viol. The instrument is especially good for playing fast sequences of notes called runs in thirds, playing two notes at the same time (double stops), and arpeggios.

The arpeggione was popular for about a decade after it was invented around 1823 by two Viennese instrument makers, Johann Georg Stauffer and Peter Teufelsdorfer. The only well-known piece written for the arpeggione is a sonata with piano accompaniment by Franz Schubert, D.821. This piece was not published until 1871, long after the instrument had fallen out of favor. Today, this sonata is often played on the cello or viola, and many other instruments have versions of the piece as well.

In the 21st century, there has been renewed interest in the arpeggione, leading to the creation of new works for the instrument alone or in groups. Composers who have written the most pieces for the arpeggione include Dov Joshua Rosenschein from the United States, Grégory Guéant from France, and René Mogensen from Denmark.

Modern instruments that resemble violins have features similar to the arpeggione. At least one of these, the GuitarViol, was directly inspired by Stauffer’s design of the arpeggione.