2003 Australian Open – Boys' singles

Clément Morel was the defending champion, but did not compete in the Juniors in this year.

Marcos Baghdatis defeated Florin Mergea (6–4, 6–4) in the final.

Seeds
• # 🇨🇾 Marcos Baghdatis (champion)

• # 🇺🇸 Brian Baker (third round)

• # 🇺🇸 Chris Kwon (first round)

• # 🇫🇷 Mathieu Montcourt (semifinals)

• # 🇫🇷 Jo-Wilfried Tsonga (semifinals)

• # 🇷🇴 Florin Mergea (final)

• # 🇷🇴 Adrian Ungur (first round)

• # 🇦🇺 Chris Guccione (third round)

• # 🇺🇸 Scott Oudsema (first round)

• # Jose-Luis Muguruza (second round)

• # 🇬🇧 David Brewer (second round)

• # 🇺🇸 Phillip Simmonds (quarterfinals)

• # 🇺🇸 Jarrett Chirico (second round)

• # 🇫🇷 Gaël Monfils (quarterfinals)

• # 🇷🇴 Horia Tecău (third round)

• # 🇩🇪 Mischa Zverev (third round)