2003 US Open – Women's singles

Justine Henin-Hardenne defeated Kim Clijsters in the final, 7–5, 6–1 to win the women's singles tennis title at the 2003 US Open. It was her first US Open title and second major title overall. She lost only one set during the tournament, to Jennifer Capriati in the semifinals.

Serena Williams was the reigning champion, but did not participate due to injury. Defending finalist and her sister Venus Williams also withdrew before the tournament due to injury, marking the first time in the Open Era that neither of the reigning US Open finalists returned. This was also the only major between the 1997 Australian Open and the 2011 French Open (a span of 56 events) where neither of the Williams sisters competed.

This marked the first US Open main draw appearance of 2015 champion Flavia Pennetta; she lost to Svetlana Kuznetsova in the first round.

Seeds
• # 🇧🇪 Kim Clijsters (final)

• # 🇧🇪 Justine Henin-Hardenne (champion)

• # 🇺🇸 Lindsay Davenport (semifinals)

• # 🇺🇸 Venus Williams (withdrew)

• # 🇫🇷 Amélie Mauresmo (quarterfinals)

• # 🇺🇸 Jennifer Capriati (semifinals)

• # 🇷🇺 Anastasia Myskina (quarterfinals)

• # 🇺🇸 Chanda Rubin (first round)

• # 🇸🇰 Daniela Hantuchová (third round)

• # 🇧🇬 Magdalena Maleeva (first round)

• # 🇷🇺 Elena Dementieva (fourth round)

• # 🇪🇸 Conchita Martínez (second round)

• # 🇷🇺 Vera Zvonareva (third round)

• # Amanda Coetzer  (third round)

• # 🇯🇵 Ai Sugiyama (fourth round)

• # 🇷🇺 Elena Bovina (first round)

• # 🇺🇸 Meghann Shaughnessy (fourth round)

• # Patty Schnyder (second round)

• # 🇷🇺 Nadia Petrova (third round)

• # 🇮🇹 Silvia Farina Elia (second round)

• # 🇮🇱 Anna Pistolesi (first round)

• # Jelena Dokić (second round)

• # 🇫🇷 Nathalie Dechy (second round)

• # 🇦🇷 Paola Suárez (quarterfinals)

• # Eleni Daniilidou (first round)

• # 🇷🇺 Lina Krasnoroutskaya (first round)

• # 🇷🇺 Svetlana Kuznetsova (third round)

• # 🇺🇸 Lisa Raymond (second round)

• # 🇮🇹 Francesca Schiavone (quarterfinals)

• # 🇪🇸 Magüi Serna (second round)

• # 🇺🇸 Alexandra Stevenson (first round)

• # Marie-Gayanay Mikaelian (second round)

• # Katarina Srebotnik (second round)