The very wealthy Dr. Plesch shared Etti Plesch's passion for Thoroughbred horse racing, something that had been influenced by her maternal grandfather Alexander Baltazzi who won the 1876 edition of the Epsom Derby with Kisber. She and her husband began racing Thoroughbreds in 1954 and would win major races such as the 1959 Coronation Cup with Nagami and that year's Irish Oaks with Discorea. Their 1961 Epsom Derby winner Psidium was bred by Etti Plesch and raced by the couple. Following her husband's death in 1974, she continued to race horses and in 1970 won France's most prestigious race with Sassafras. In 1980, Etti Plesch became the only female owner to ever win the Epsom Derby twice when her horse Henbit won England's most prestigious race.