Quarteto em Cy (a play on words of the Portuguese for Quartet in B by poet and lyricist Vinicius de Moraes) is a Brazilian girl group originally composed of four sisters hailing from Ibirataia, a town located in the Brazilian state of Bahia: Cybele, Cylene, Cynara and Cyva - their real first names.
In his career, Mario Negrão accompanied as instrumentalist Baden Powell, Carlos Lyra, Claudete Soares, Clara Nunes, Chico Buarque, Egberto Gismonti, Leila Pinheiro, MPB4, Paulinho Nogueira, Quarteto em Cy, Rosinha de Valença, Sergio Ricardo, Tom Jobim, Toquinho, Vinícius de Moraes, among others.