The Quarteto em Cy, noted for the extraordinary precision of the vocalists' intonation and delivery, performed and recorded with almost every single major Brazilian artist of the 60s and 70s; their popularity exceeded and still exceeds the borders of their native country. They met with great success in America in the mid-sixties, and have a considerable following in Japan, where they still tour regularly.

The line-up of the quartet (which briefly split up, from 1970 to 1972) has changed a great deal over the years. However, the current formation (Cyva, Cybele, Cynara and Sonya) has been active since 1980, by far the most stable period in the group's history.