See main article: 1999 Open Gaz de France.
The 1999 Open Gaz de France singles was the singles event of the seventh edition of the Open GDF Suez; a WTA Tier II tournament held in Paris, France. Mary Pierce was the defending champion but did not compete that year.
Serena Williams won in the final 6–2, 3–6, 7–6(7–4) against Amélie Mauresmo. It was her first career singles title.
The top four seeds received a bye to the second round.