2004 French Open – Men's singles

Gastón Gaudio defeated Guillermo Coria in the final, 0–6, 3–6, 6–4, 6–1, 8–6 to win the men's singles tennis title at the 2004 French Open. It was his first and only major title, and Gaudio became the first Argentine to win a major since Guillermo Vilas at the 1979 Australian Open. Gaudio came back from two sets down, saved two championship points, and twice broke Coria's serve when the latter was serving for the championship.

Juan Carlos Ferrero was the defending champion, but was defeated in the second round by Igor Andreev, in what was his first loss at the French Open prior to the semifinals.

This was the first major where Roger Federer competed as the world No. 1. He lost in the third round to former No. 1 and three-time champion Gustavo Kuerten, in his last pre-quarterfinal exit from a major until the 2013 Wimbledon Championships, a run of 36 quarterfinals or better in a row. Until 2023, this was the last French Open not to feature future 14-time champion Rafael Nadal, who withdrew prior to the tournament due to an ankle injury sustained in Estoril in mid-April.

This was the first major in the Open Era to feature four Argentines in the quarterfinals, those being Gaudio, Coria, David Nalbandian, and Juan Ignacio Chela.

Wayne Ferreira matched Stefan Edberg's all-time record on his 54th consecutive major main draw appearance.

The first round match between Fabrice Santoro and Arnaud Clément was the then-longest match of the Open Era, lasting 6 hours and 33 minutes and played over two days. John Isner and Nicolas Mahut would later break this record with their first-round singles match at the 2010 Wimbledon Championships.

Seeds
• Roger Federer (third round)

• 🇺🇸 Andy Roddick (second round)

• 🇦🇷 Guillermo Coria (final)

• 🇪🇸 Juan Carlos Ferrero (second round)

• 🇪🇸 Carlos Moyá (quarterfinals)

• 🇺🇸 Andre Agassi (first round)

• 🇩🇪 Rainer Schüttler (first round)

• 🇦🇷 David Nalbandian (semifinals)

• 🇬🇧 Tim Henman (semifinals)

• 🇫🇷 Sébastien Grosjean (second round)

• Nicolás Massú (third round)

• 🇦🇺 Lleyton Hewitt (quarterfinals)

• 🇹🇭 Paradorn Srichaphan (second round)

• 🇨🇿 Jiří Novák (second round)

•  Sjeng Schalken (withdrew because of a viral infection)

•  Fernando González (first round)

• 🇪🇸 Tommy Robredo (fourth round)

• 🇦🇺 Mark Philippoussis (first round)

•  Martin Verkerk (third round)

• 🇷🇺 Marat Safin (fourth round)

•  Andrei Pavel (second round)

• 🇦🇷 Juan Ignacio Chela (quarterfinals)

• 🇪🇸 Feliciano López (fourth round)

• 🇸🇪 Jonas Björkman (second round)

•  Ivan Ljubičić (second round)

• 🇪🇸 Albert Costa (third round)

• 🇺🇸 Vince Spadea (second round)

• 🇧🇷 Gustavo Kuerten (quarterfinals)

• 🇧🇾 Max Mirnyi (first round)

• 🇦🇷 Mariano Zabaleta (second round)

• 🇸🇰 Dominik Hrbatý (second round)

• 🇫🇷 Arnaud Clément (first round)