Rio-Sul Serviços Aéreos Regionais S/A was a regional airline headquartered in Rio de Janeiro, Brazil, operating scheduled services to southern Brazil. Its main base was São Paulo–Congonhas Airport, with hubs at Porto Alegre Airport and Santos Dumont Airport.

VARIG was the first airline founded in Brazil, in 1927. From 1965 until 1990, it was Brazil's leading airline and virtually its only international one. In 2005, Varig went into judicial restructuring, and in 2006 it was split into two companies – Flex Linhas Aéreas, informally known as "old" Varig, heir to the original airline – now defunct, and "new" Varig, a new company, fully integrated into Gol Airlines.