2003 US Open – Boys' singles

Richard Gasquet was the defending champion, but did not compete in the juniors that year.

Jo-Wilfried Tsonga won the tournament, defeating Marcos Baghdatis in the final, 7–6(7–4), 6–3.

Seeds
• # 🇨🇾 Marcos Baghdatis (final)

• # 🇷🇴 Florin Mergea (semifinals)

• # 🇺🇸 Brian Baker (quarterfinals)

• # 🇮🇱 Dudi Sela (semifinals)

• # 🇫🇷 Jo-Wilfried Tsonga (champion)

• # 🇪🇸 Daniel Gimeno-Traver (third round)

• # 🇫🇷 Mathieu Montcourt (quarterfinals)

• # 🇦🇺 Chris Guccione (third round)

• # 🇩🇪 Sebastian Rieschick (third round)

• # 🇺🇸 Chris Kwon (first round)

• # 🇧🇷 Bruno Rosa (second round)

• # 🇬🇧 Andy Murray (quarterfinals)

• # Fred Gil (third round)

• # 🇲🇽 Luis-Manuel Flores (third round)

• # 🇧🇷 Leonardo Kirche (second round)

• # 🇰🇷 Suk Hyun-joon (second round)