2003 Australian Open – Women's singles

Serena Williams defeated her sister Venus Williams in the final, 7–6(7–4), 3–6, 6–4 to win the women's singles tennis title at the 2003 Australian Open. It was her fourth consecutive major singles triumph, completing the "Serena Slam", both a non-calendar year Grand Slam and the career Grand Slam. It was also Venus' record fourth consecutive runner-up finish at a major, losing every final to Serena. Serena saved two match points en route to the title, against Kim Clijsters in the semifinals (where at one point in the third set Serena was 1–5 down).

Jennifer Capriati was the two-time defending champion, but lost to Marlene Weingärtner in the first round. Capriati's loss marked the first time the defending Australian Open champion lost in the first round, and the first time at any major that the defending champion lost in the first round since Steffi Graf at the 1994 Wimbledon Championships. With Lindsay Davenport's defeat in the fourth round, a first-time Australian Open champion was guaranteed.

This tournament marked the first Australian Open final without Martina Hingis since 1996. It was also the final appearance of four-time champion Monica Seles, who lost to Klára Koukalová in the second round.

This marked the first major appearance of two future world No. 1's: five-time major champion Maria Sharapova and Jelena Janković, who lost to Klára Koukalová and Amanda Coetzer in the first and second rounds respectively. It was also the major main draw debut of future US Open champion Flavia Pennetta, who lost to Silvia Farina Elia in the first round.

Seeds
• # 🇺🇸 Serena Williams (champion)

• # 🇺🇸 Venus Williams (final)

• # 🇺🇸 Jennifer Capriati (first round)

• # 🇧🇪 Kim Clijsters (semifinals)

• # 🇧🇪 Justine Henin-Hardenne (semifinals)

• # 🇺🇸 Monica Seles (second round)

• # 🇸🇰 Daniela Hantuchová (quarterfinals)

• # 🇷🇺 Anastasia Myskina (quarterfinals)

• # 🇺🇸 Lindsay Davenport (fourth round)

• # 🇺🇸 Chanda Rubin (fourth round)

• # 🇧🇬 Magdalena Maleeva (third round)

• # Patty Schnyder (fourth round)

• # 🇮🇹 Silvia Farina Elia (second round)

• # 🇮🇱 Anna Pistolesi (third round)

• # 🇺🇸 Alexandra Stevenson (second round)

• # 🇫🇷 Nathalie Dechy (third round)

• # 🇷🇺 Elena Dementieva (first round)

• # Eleni Daniilidou (fourth round)

• # Amanda Coetzer (fourth round)

• # 🇷🇺 Elena Bovina (fourth round)

• # 🇯🇵 Ai Sugiyama (second round)

• # 🇱🇺 Anne Kremer (second round)

• # 🇦🇷 Paola Suárez (third round)

• # 🇷🇺 Tatiana Panova (third round)

• # 🇺🇸 Meghann Shaughnessy (quarterfinals)

• # 🇹🇭 Tamarine Tanasugarn (third round)

• # 🇺🇸 Lisa Raymond (second round)

• # 🇦🇷 Clarisa Fernández (third round)

• # Iva Majoli (first round)

• # 🇸🇰 Janette Husárová (second round)

• # 🇪🇸 Conchita Martínez (first round)

• # Katarina Srebotnik (third round)

Wild cards
• 🇬🇧 Elena Baltacha

• 🇦🇺 Casey Dellacqua

• 🇦🇺 Evie Dominikovic

• 🇦🇺 Rachel McQuillan

• 🇯🇵 Akiko Morigami

• 🇫🇷 Camille Pin

• 🇦🇺 Samantha Stosur

• 🇦🇺 Adriana Szili

Protected ranking
• 🇪🇸 Anabel Medina Garrigues

Qualifiers
• 🇺🇸 Ansley Cargill

• 🇭🇺 Melinda Czink

• 🇸🇰 Eva Fislová

• 🇸🇰 Stanislava Hrozenská

• Jelena Janković

• 🇨🇿 Klára Koukalová

• 🇺🇸 Lindsay Lee-Waters

• 🇪🇸 Nuria Llagostera Vives

• 🇦🇷 María Emilia Salerni

• 🇦🇹 Barbara Schwartz

• 🇷🇺 Maria Sharapova

• 🇨🇦 Vanessa Webb

Withdrawals
• Martina Hingis → replaced by 🇪🇸 María Sánchez Lorenzo

• 🇫🇷 Amélie Mauresmo → replaced by 🇷🇺 Nadia Petrova