Repetition is important in music, where sounds or sequences are often repeated. It may be called restatement, such as the restatement of a theme. While it plays a role in all music, with noise and musical tones lying along a spectrum from irregular to periodic sounds, it is especially prominent in specific styles.

A literal repetition of a musical passage is often indicated by the use of a repeat sign, or the instructions da capo or dal segno.

Repetition is a part and parcel of symmetry—and of establishing motifs and hooks. You find a melodic or rhythmic figure that you like, and you repeat it throughout the course of the melody or song. This sort of repetition...helps to unify your melody; it's the melodic equivalent of a steady drumbeat, and serves as an identifying factor for listeners. However, too much of a good thing can get annoying. If you repeat your figure too often, it will start to bore the listener.

— (Miller, 106)

Memory affects the music-listening experience so profoundly that it would not be hyperbole to say that without memory there would be no music. As scores of theorists and philosophers have noted...music is based on repetition. Music works because we remember the tones we have just heard and are relating them to the ones that are just now being played. Those groups of tones—phrases—might come up later in the piece in a variation or transposition that tickles our memory system at the same time as it activates our emotional centers...(Levitin, 162–163)

Theodor W. Adorno damned repetition and popular music as psychotic and infantile. In contrast, Richard Middleton (1990) argues that "while repetition is a feature of all music, of any sort, a high level of repetition may be a specific mark of 'the popular'" and that this allows an "enabling" of "an inclusive rather than exclusive audience". "There is no universal norm or convention" for the amount or type of repetition; "all music contains repetition – but in differing amounts and of an enormous variety of types". This is influenced by "the political economy of production; the 'psychic economy' of individuals; the musico-technological media of production and reproduction (oral, written, electric); and the weight of the syntactic conventions of music-historical traditions".

Middleton distinguishes between discursive and musematic repetition. A museme is a minimal unit of meaning, analogous to a morpheme in linguistics, and musematic repetition is "at the level of the short figure, often used to generate an entire structural framework". Discursive repetition is "at the level of the phrase or section, which generally functions as part of a larger-scale 'argument'". He gives "paradigmatic case[s]": the riff and the phrase. Musematic repetition includes circularity, synchronic relations, and openness. Discursive repetition includes linearity, rational control, and self-sufficiency. Discursive repetition is most often nested (hierarchically) in larger repetitions and may be thought of as sectional, while musematic repetition may be thought of as additive. Put more simply, musematic repetition is simple repetition of precisely the same musical figure, such as a repeated chorus. Discursive repetition is "both repetitive and non-repetitive" (Lott, p. 174), such as the repetition of the same rhythmic figure with different notes.

During the Classical era, musical concerts were highly expected events, and because someone who liked a piece of music could not listen to it again, musicians had to think of a way to make the music sink in. Therefore, they would repeat parts of their song at times, making music like sonatas very repetitive, without being dull.