 She competed for the United States, winning a Gold medal at the 1984 Summer Olympics held in Los Angeles as a member of the 4 x 400 metres relay team, running in the preliminary rounds with her sister Sherri running in the final.It was a reversal at the 1988 Summer Olympics held in Seoul, South Korea in the 4 x 400 metres relay, where both sisters won the Silver medal, but Denean ran in the final with her teammates Diane Dixon, Valerie Brisco-Hooks and Florence Griffith Joyner.The team set the current standing American Record in the event, which is still the second best time ever run behind the winning Soviet team in that race.