Defending champion Juan Carlos Ferrero defeated Guillermo Coria in the final, 6–2, 6–2 to win the singles tennis title at the 2003 Monte Carlo Masters. This was a breakthrough tournament for future eleven-time champion Rafael Nadal. With his second round victory over defending French Open champion Albert Costa, he entered the world's Top 100 in the ATP rankings for the first time. He lost to Coria in the third round, which would remain his sole loss at the tournament until 2013.

Seeds

• # 🇪🇸 Juan Carlos Ferrero (champion) • # 🇪🇸 Carlos Moyá (semifinals) • # 🇺🇸 Andy Roddick (first round) • # 🇪🇸 Albert Costa (second round) • # 🇨🇿 Jiří Novák (second round) • # 🇦🇷 David Nalbandian (second round) • # 🇹🇭 Paradorn Srichaphan (second round) • # 🇩🇪 Rainer Schüttler (second round) • # Sjeng Schalken (third round) • # 🇧🇷 Gustavo Kuerten (second round) • # 🇲🇦 Younes El Aynaoui (first round) • # 🇪🇸 Àlex Corretja (first round) • # 🇦🇷 Gastón Gaudio (third round) • # Fernando González (first round) • # 🇺🇸 James Blake (second round) • # 🇪🇸 Tommy Robredo (third round)

Draw

Finals

Top half

Section 1

Section 2

Bottom half

Section 3

Section 4