Following a brief hiatus after the departure of former bandmembers Champignon, Marcão and Renato Pelado, it was the band's first release with its new line-up of bassist Heitor Gomes, drummer/beatboxer Pinguim Ruas and guitarist Thiago Castanho, an original founding member who had parted ways with Charlie Brown Jr. in 2001 following the release of their third album, Nadando com os Tubarões.

[1] It spawned four hit singles, the most noteworthy being "Lutar pelo que É Meu" (used as the theme song of the 13th season of long-running soap opera Malhação), "Ela Vai Voltar (Todos os Defeitos de uma Mulher Perfeita)" (featured in the 21st season of the soap opera but not included in its soundtrack CD) and "Pra Não Dizer que Não Falei das Flores", a cover of the famous anti-dictatorship song written by Geraldo Vandré in the late 1960s.

Counting with guest appearances by Rappin' Hood, hip hop group Sacramento MCs and Nigerian-born musician Osas Destiny (at the time still a member of group Conexão Baixada and credited by his former stage name JamaicaBoy), the album was received positively upon its release, with many praising the new line-up as a "breath of fresh air".

In 2006, Imunidade Musical was nominated for a Latin Grammy Award for Best Portuguese Language Rock or Alternative Album; it was the band's third album to receive a nomination following Nadando com os Tubarões and Bocas Ordinárias.

Anderson Nascimento of Galeria Musical gave the album a positive rating of 4 out of 5 stars, praising it as one of the most "complete and inspired" releases by Charlie Brown Jr. but criticizing its length.