When she was 14, Barros and her older sister, Patricia (also a model)who at the time lived in Toronto were having vacation in Rio when they were spotted by a representative from Elite Model Management .Barros was encouraged by the Rio Elite office to participate in the Elite Model Look 1996, which she won. Barros subsequently competed for international Elite Model Look and placed second worldwide . Elite sent her portfolio and recent Polaroid shots to GUESS? which led her to do the Millennium GUESS? campaign along with her friend and fellow Brazilian model Alessandra Ambrosio . Barros has done advertisements not only for Guess? but also for Christian Dior, Armani jeans, Oakley, L'Oreal, Naf Naf, Diesel, Ermanno Scervino, Victoria's Secret, Chanel cosmetics, and Jennifer Lopez's JLO fashion line, among others. In 2004 Jennifer Lopez selected Barros to be the face of her new lingerie line, JLO Lingerie.