She won the bronze medal in the women's 4×100 m freestyle relay at the Pan American Games in Santo Domingo, Dominican Republic.

Gusmão won the women's 50 and 100 freestyle events at the 2007 Pan Ams; however, all her results (times and placings) from those Games were later nullified due to a positive doping-control test.

On November 5, 2007, Rebeca Gusmão received a provisionally suspension by FINA, the International Swimming Federation, for a positive out-of-competition doping control result for testosterone taken on July 13, 2007.

[1][2] On December 13, 2007, PASO declared Rebeca Gusmão guilty of doping with testosterone and revoked her XV Pan American Games medals.

On May 16, 2008, the FINA Doping Panel declared Gusmão ineligible for 2 years (beginning November 2, 2007) for the out-of-competition result.