An arpeggio (Italian: [arˈpeddʒo]) is a type of broken chord in which the notes that compose a chord are individually sounded in a progressive rising or descending order. Arpeggios on keyboard instruments may be called rolled chords.

Arpeggios may include all notes of a scale or a partial set of notes from a scale, but must contain notes of at least three pitches (two-pitch sequences are known as trills). Arpeggios may sound notes within a single octave or span multiple octaves, and the notes may be sustained and overlap or be heard separately. An arpeggio for the chord of C major going up two octaves would be the notes (C, E, G, C, E, G, C).

In musical notation, a very rapid arpeggiated chord may be written with a wavy vertical line in front of the chord. Typically these are read as to be played from the lowest to highest note, though composers may specify a high to low sequence by adding an arrow pointing down.

Arpeggios enable composers writing for monophonic instruments that play one note at a time (such as the trumpet), to voice chords and chord progressions in musical pieces. Arpeggios are also used to help create rhythmic interest, or as melodic ornamentation in the lead or accompaniment.

Though the notes of an arpeggio are not sounded simultaneously, listeners may effectively hear the sequence of notes as forming a chord if played in quick succession. When an arpeggio also contains passing tones that are not part of the chord, certain music theorists may analyze the same musical excerpt differently.

The word arpeggio comes from the Italian word arpeggiare, which means to play on a harp. Despite its Italian origins, its plural usage is usually arpeggios rather than arpeggi.