Os Mutantes were one of the most dynamic and radical bands of the psychedelic era. A trio of musical experimentalists from Brazil, the group played with distortion, feedback, musique concrète, and studio techniques to create a playful, energetic version of Brazilian pop.

The band was formed by Arnaldo and Sérgio Baptista, the sons of a celebrated São Paulo concert pianist. With Arnaldo on bass and keyboards and Sérgio on guitar, and vocalist Rita Lee, the three played in the Six Sided Rockers. In 1965, they formed Os Mutantes and their brother, Cláudio, joined on electronics. The group played each week on the Brazilian TV show “O Pequeno Mundo de Ronnie Von” and became involved with the burgeoning tropicalia movement. Mutantes backed Gilberto Gil at the third annual Festival of Brazilian Music in 1967, and appeared on the 1968 LP Tropicalia: Ou Panis et Circenses, a compilation of songs from the movement's major figures.

By the end of 1968, Os Mutantes delivered their self-titled debut, a raucous record featuring a panoply of environmental sounds and distorted guitar lines. After backing Veloso and recording a second LP, the band traveled to Europe and performed at several music conferences. Returning to Brazil, the group recorded Divina Comedia Ou Ando Meio Desligado in 1970 and Jardim Eletrico in 1971, both of which charted the band's shifting interests from psychedelic to blues and hard rock.

After 1972's E Seus Cometas No Pais Do Baurets, Rita Lee left the group to pursue a solo career. After Arnaldo Baptista left the group, the band's LPs included a succession of bandmembers, producer Liminha, keyboard player Túlio, and drummer Rui Motta. Except for a live record, 1974's Tudo Foi Feito Pelo Sol was the band's final LP. David Byrne assembled the compilation Everything Is Possible through Luaka Bop.

In May of 2006, Os Mutantes (featuring Arnaldo and Sérgio with vocalist Zélia Duncan) played live for the first time since 1978 at the Tropicalia exhibition at London's Barbican Arts Centre. The performance was followed by shows in New York City, Los Angeles, San Francisco, Seattle, Denver, Chicago, and Miami.