In the first decade of the 20th century Katie Gilou was a tennis pioneer, winning multiple titles at the French Open in the amateur era of the tournament. Prior to 1925 only players who were members of French clubs were eligible to compete, with Gilou winning the singles title on four occasions (1904–06, 1908). She also won the doubles title in 1908 with Cecile Matthey, along with two mixed doubles titles with the great Max Decugis (1904, 1908). At the 1900 Paris Olympics she partnered Maurice Germot in the mixed doubles, which was a handicap non-medal event. The pair reached the final where they lost to the Prévost siblings, André and Yvonne.