An alphabetical list of the 22 teams competing in the 2003 Tour de France, each having nine riders. The teams are named after their main sponsor. The country is merely indicative of the sponsor. The name after the country is the team leader, but often the team leadership is not as clear-cut as a single name would appear to indicate. Also, the country and team leader often do not match. For example, only one team sponsored by a company in an English-speaking country appeared in the 2003 Tour, but the list of team leaders included three Americans, a Briton, and an Australian.
- AG2R Prevoyance (France, Laurent Brochard)
- Alessio (Italy, Laurent Dufaux)
- Bianchi (Germany, Jan Ullrich)
- Brioches la Boulangere (France, Didier Rous)
- Cofidis (France, David Millar)
- Crédit Agricole (France, Christophe Moreau)
- Team CSC (Denmark, Tyler Hamilton)
- Euskaltel-Euskadi (Spain (Basque), Iban Mayo)
- Fassa Bortolo (Italy, Ivan Basso)
- FdJeux (France, Sandy Casar)
- Gerolsteiner (Germany, Davide Rebellin)
- iBanesto.com (Spain, Francesco Mancebo)
- Jean Delatour (France, Patrice Halgand)
- Kelme-Costa Blanca (Spain, Ignacio Gutierrez)
- Lotto-Domo (Belgium, Robbie McEwen)
- ONCE-Eroski (Spain, Joseba Beloki)
- Quick-Step-Davitamon (Belgium, Paolo Bettini)
- Rabobank (Netherlands, Levi Leipheimer)
- Saeco (Italy, Gilberto Simoni)
- Team Telekom (Germany, Santiago Botero)
- U.S. Postal (USA, Lance Armstrong)
- Vini Caldirola (Italy, Stefano Garzelli)