Elli Medeiros was born in Montevideo, Uruguay. Her mother, Mirtha Medeiros, decided to become an actress after Elli was born, & when she was admitted into Uruguay's Escuela National, had to take her along, so Elli attended drama school & classes by spanish teacher Pepe Struch before kindergarden. Mirtha graduated and quickly became a very busy actress and Elli was regularly hired each time a child was needed in a play or a TV show. Her first part, at age 4, was Madame Butterfly's son, in the production of Puccini's opera at the Montevideo Opera. This was Orson Welles' first role, at the same age! Elli's father, José Luis Medeiros, vanished from her life when she was five. Elli attended the Uruguayan American School, and when her mother remarried & they moved to Buenos Aires, Argentina, she attended the Instituto Bayard, a British school .

When she was fourteen, her mother & step father moved to Paris, and she had to learn french in a couple of months so she could attend high school. She tried several schools, including an art schoot, l'Ecole des Arts Appliquées, but dropped out before getting a "baccalauréat" to start her first band, the Stinky Toys, the first french punk band, playing several London punk Festivals along with the Clash & the Sex Pistols. Elli appeared on the cover of Melody Maker & that convinced the until then extremely reluctant french record companies, to sign them a deal. After two albums, the Stinky Toys split and Elli and Stinky Toy Jacno then released several albums as the techno pop duo Elli & Jacno. Their last was Les Nuits de la Pleine Lune, score to Eric Rohmer 's movie. Elli then went solo, her music becoming more personal, more latin and had several hits in France, including Toi Mon Toit and A bailar Calypso, mega hits of 1986 and 1987, now standards. After a break, Elli decided to go back to acting & school, & worked with Andreas Voutsinas, who was Lee Strasberg's assistant for twenty years and created the Paris "Actor's Studio", le Théatre des Cinquante. She also took classes with Madeleine Barchevska and Bob Mc Andrew.