One of the most underrated, important, and influential arrangers of Brazilian popular music after the 1950s, Leo Peracchi started to contribute to the soon-to-be bossa nova in 1956 when he arranged "Foi a Noite," by the then-novice composer Tom Jobim (with Newton Mendonça), recorded by Silvinha Telles. Having written the arrangements for Ary Barroso's Meu Brasil Brasileiro (1959), in the same year he also arranged 13 songs by the duo Jobim/Vinícius de Moraes, which would become immortal classics. The songs were recorded by Peracchi's wife, Lenita Bruno, for the LP Por Toda a Minha Vida, and the same orchestrations re-recorded in a careful production in 2002 by Ná Ozzetti, Mônica Salmaso, Vânia Bastos, Tetê Espíndola, Jane Duboc, Céline Imbert, Myriam Peracchi, and the Orquestra Jazz Sinfônica. As a conductor, orchestrator, and composer at Rádio Nacional, Peracchi had a noted contribution in the highly influential role of Nacional in the modernization of Brazilian radio, as it was the Nacional which, with its immense resources and nationwide reach, infused into the Brazilian audience the taste for sophisticated orchestrations and arrangements for symphonic orchestras and small chamber groups aired live from its studios, which ended up as a recording standard of the period extended through the '40s until the late '50s.
Peracchi started as a professional pianist and conductor at Rádio Cosmos, São Paulo (São Paulo), having worked also at radios Bandeirantes and Educadora Paulista. In 1941, he became a member of the regular cast of the powerful Rádio Nacional (Rio de Janeiro, Rio de Janeiro) as an orchestrator, conductor, and composer, giving an important contribution to the modernization of the standards of communication in radio. Among the several programs he worked in deserving mention were Dona Música, created by him (with Haroldo Barbosa/José Mauro); the Festivais GE, a show dedicated to the classical repertory in which, for ten years, Peracchi conducted live a symphonic orchestra; Quando os Maestros se Encontram, in which Peracchi was confronted with other conductors of the cast like Alexandre Gnattali, Lyrio Panicali, Alberto Lazzoli, and Alceu Bocchino; and Instantâneos Musicais, created by Almirante at Rádio Nacional. As an arranger, he worked for several artists and groups on their recordings and live performances, like the Trio Surdina on its LP dedicated to Ary Barroso's songs, having also recorded several individual albums ahead of different orchestras from 1955 to 1968. In 1959, he led the second musical caravan organized by the Brazilian government by initiative of Humberto Teixeira to promote Brazilian music in Europe. In the '50s, he also became the music director at the Musidisc label.